Connect public, paid and private patent data with Google Patents Public Datasets

Data storage device saving absolute position at each servo wedge for previous write operations

Download PDF

Info

Publication number
US9355667B1
US9355667B1 US14538610 US201414538610A US9355667B1 US 9355667 B1 US9355667 B1 US 9355667B1 US 14538610 US14538610 US 14538610 US 201414538610 A US201414538610 A US 201414538610A US 9355667 B1 US9355667 B1 US 9355667B1
Authority
US
Grant status
Grant
Patent type
Prior art keywords
write
track
position
data
servo
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
US14538610
Inventor
Nathan J. Santee
Yanan Huang
Wei Xi
Hien T. Chu
Orhan Beker
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Western Digital Technologies Inc
Original Assignee
Western Digital Technologies Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Grant date

Links

Images

Classifications

    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/48Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed
    • G11B5/58Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
    • G11B5/596Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following for track following on disks
    • G11B5/59633Servo formatting
    • G11B5/59655Sector, sample or burst servo format
    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B19/00Driving, starting, stopping record carriers not specifically of filamentary or web form, or of supports therefor; Control thereof; Control of operating function ; Driving both disc and head
    • G11B19/02Control of operating function, e.g. switching from recording to reproducing
    • G11B19/04Arrangements for preventing, inhibiting, or warning against double recording on the same blank or against other recording or reproducing malfunctions
    • G11B19/041Detection or prevention of read or write errors
    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/10Digital recording or reproducing
    • G11B20/10527Audio or video recording; Data buffering arrangements
    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/10Digital recording or reproducing
    • G11B20/12Formatting, e.g. arrangement of data block or words on the record carriers
    • G11B20/1217Formatting, e.g. arrangement of data block or words on the record carriers on discs
    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/012Recording on, or reproducing or erasing from, magnetic disks
    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/48Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed
    • G11B5/58Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
    • G11B5/596Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following for track following on disks
    • G11B5/59627Aligning for runout, eccentricity or offset compensation
    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/48Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed
    • G11B5/58Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
    • G11B5/596Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following for track following on disks
    • G11B5/59633Servo formatting
    • G11B5/59644Acquisition or selection of servo format from a system reference
    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/10Digital recording or reproducing
    • G11B20/12Formatting, e.g. arrangement of data block or words on the record carriers
    • G11B2020/1264Formatting, e.g. arrangement of data block or words on the record carriers wherein the formatting concerns a specific kind of data
    • G11B2020/1265Control data, system data or management information, i.e. data used to access or process user data
    • G11B2020/1281Servo information

Abstract

A data storage device is disclosed comprising a head actuated over a disk comprising a plurality of tracks defined by servo sectors, wherein each servo sector comprises a plurality of servo bursts and the servo sectors define a plurality of servo wedges. A first write operation is executed to a first track and a first absolute position for the head is generated corresponding to a first servo wedge. A second write operation is executed to a second track and a second absolute position for the head is generated corresponding to the first servo wedge. An off-track write condition is detected when executing the second write operation based on the first absolute position and the second absolute position. The first absolute position comprises a track address of the first track and a position error measurement based on the servo bursts in the first servo wedge.

Description

BACKGROUND

Disk drives comprise a disk and a head connected to a distal end of an actuator arm which is rotated about a pivot by a voice coil motor (VCM) to position the head radially over the disk. The disk comprises a plurality of radially spaced, concentric tracks for recording user data sectors and servo sectors. The servo sectors comprise head positioning information (e.g., a track address) which is read by the head and processed by a servo control system to control the actuator arm as it seeks from track to track.

FIG. 1 shows a prior art disk format 2 as comprising a number of servo tracks 4 defined by servo sectors 6 0-6 N recorded around the circumference of each servo track. Each servo sector 6, comprises a preamble 8 for storing a periodic pattern, which allows proper gain adjustment and timing synchronization of the read signal, and a sync mark 10 for storing a special pattern used to symbol synchronize to a servo data field 12. The servo data field 12 stores coarse head positioning information, such as a servo track address, used to position the head over a target data track during a seek operation. Each servo sector 6 i further comprises groups of servo bursts 14 (e.g., N and Q servo bursts), which are recorded with a predetermined phase relative to one another and relative to the servo track centerlines. The phase based servo bursts 14 provide fine head position information used for centerline tracking while accessing a data track during write/read operations. A position error signal (PES) is generated by reading the servo bursts 14, wherein the PES represents a measured position of the head relative to a centerline of a target servo track. A servo controller processes the PES to generate a control signal applied to a head actuator (e.g., a voice coil motor) in order to actuate the head radially over the disk in a direction that reduces the PES.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a prior art disk format comprising a plurality of tracks defined by servo sectors that form servo wedges.

FIG. 2A shows a data storage device in the form of a disk drive according to an embodiment comprising a head actuated over a disk comprising a plurality of tracks defined by servo sectors, wherein each servo sector comprises a plurality of servo bursts and the servo sectors define a plurality of servo wedges.

FIG. 2B is a flow diagram according to an embodiment wherein an absolute position of the head is evaluated to detect an off-track write condition.

FIG. 2C illustrates an off-track write condition detected based on the absolute positions of adjacent track writes according to an embodiment.

FIGS. 3A-3D illustrate an embodiment wherein the absolute position of the head at each servo wedge during write operations is saved in a position buffer representing a circumference of the disk.

FIG. 4 is a flow diagram according to an embodiment wherein the position buffer is updated based on a current write operation.

FIG. 5 is a flow diagram according to an embodiment wherein an off-track write condition may be detected based on the absolute position of the head and an absolute reference position.

FIG. 6 is a flow diagram according to an embodiment wherein when an off-track write condition is detected, at least one data wedge of the previously written, adjacent track is rewritten.

FIG. 7 is a flow diagram according to an embodiment wherein an off-track write condition may be predicted before it occurs.

FIG. 8 shows an embodiment wherein the disk is divided into a number of radial zones, wherein each radial zone is tracked using a position buffer and a data buffer.

FIG. 9A shows a data storage device in the form of a disk drive according to an embodiment comprising a head actuated over a disk.

FIG. 9B is a flow diagram according to an embodiment wherein an off-track write threshold is selected based on a write throughput and a read throughput of the data storage device.

FIG. 10 illustrates an embodiment wherein the off-track write threshold is selected as the minimum of the measured off-track write thresholds that substantially maximizes the write throughput biased by a first weighting and the read throughput biased by a second weighting.

DETAILED DESCRIPTION

FIG. 2A shows a data storage device in the form of a disk drive according to an embodiment comprising a head 16 actuated over a disk 18 comprising a plurality of tracks 20 defined by servo sectors 22 0-22 N, wherein each servo sector comprises a plurality of servo bursts and the servo sectors 22 0-22 N define a plurality of servo wedges. The disk drive further comprises control circuitry 24 configured to execute the flow diagram of FIG. 2B, wherein a first write operation is executed to a first track and a first absolute position for the head is generated corresponding to a first servo wedge (block 26). A second write operation is executed to a second track and a second absolute position for the head is generated corresponding to the first servo wedge (block 28). An off-track write condition is detected (block 32) when executing the second write operation based on the first absolute position and the second absolute position (block 30). The first absolute position comprises a track address of the first track and a position error measurement based on the servo bursts in the first servo wedge.

In the embodiment of FIG. 2A, the servo sectors 22 0-22 N define a plurality of servo tracks, wherein data tracks are defined relative to the servo tracks at the same or different radial density. The control circuitry 24 processes a read signal 34 emanating from the head 16 to demodulate the servo sectors 22 0-22 N and generate a position error signal (PES) representing an error between the actual position of the head and a target position relative to a target track. The control circuitry 24 filters the PES using a suitable compensation filter to generate a control signal 36 applied to a voice coil motor (VCM) 38 which rotates an actuator arm 40 about a pivot in order to actuate the head 16 radially over the disk 18 in a direction that reduces the PES. The servo sectors 22 0-22 N may comprise any suitable head position information, such as a track address for coarse positioning and servo bursts for fine positioning. The servo bursts may comprise any suitable pattern, such as an amplitude based servo pattern or a phase based servo pattern.

During a write operation, the head 16 may deviate from the center of the target track resulting in an off-track write condition. In one embodiment shown in FIG. 2C, the off-track write condition is detected relative to the absolute position of the head 16 when writing a current track n+1 and the absolute position of the head 16 when writing a previous track n. For example, if the difference between the absolute positions is less than a threshold at block 30 of FIG. 2B, then an off-track write condition is detected. Referring to the example of FIG. 2C, an off-track write condition is not detected at servo wedge SS[i] whereas an off-track write condition is detected at servo wedge SS[i+1]. In one embodiment, in order to detect the off-track write condition, the absolute position of the head when writing the adjacent track n is saved in a position buffer. In one embodiment, the position buffer stores an absolute position corresponding to each servo wedge so that if the entire track n is written, then each entry of the position buffer is updated with the absolute position generated at each servo wedge. In one embodiment, write operations may be executed to non-adjacent tracks (including partial tracks) such that the position buffer may store the absolute position for each servo wedge that may correspond to different, non-adjacent tracks.

An example of this embodiment is illustrated in FIGS. 3A-3D which illustrate how the position buffer may be updated when executing a number of write operations. This example shows the disk 18 may comprise 14 servo wedges (0-13); however, the disk 18 may comprise any suitable number of servo wedges. FIG. 3A shows a first write operation to a first track n, wherein the first write operation spans servo wedges 2-6 and therefore a corresponding absolute position generated at servo wedges 2-6 is stored in the position buffer. FIG. 3B shows a second write operation to a second, adjacent track n+1, wherein the second write operation spans servo wedges 4-10 and therefore a corresponding absolute position generated at servo wedges 4-10 is stored in the position buffer. In this example, the absolute position previously stored in the position buffer for servo wedges 4-6 when executing the first write operation (FIG. 3A) are overwritten with the absolute position generated for servo wedges 4-6 during the second write operation (FIG. 3B).

When executing the second write operation, the absolute position generated at servo wedge 4 may be compared to the absolute position saved in the position buffer in order to detect an off-track write condition. If the off-track write condition is not detected, the absolute position generated at servo wedge 4 during the second write operation may replace the absolute position previously stored in the position buffer. In an alternative embodiment, the absolute position generated at each servo wedge during the second write operation may be stored in a scratch buffer. If the second write operation completes successfully without detecting an off-track write condition, then the absolute position values stored in the scratch buffer may replace the absolute position values stored in the position buffer. This embodiment may facilitate rewriting one or more of the data wedges during a retry write operation if an off-track write condition is detected.

FIG. 3C shows a third write operation to a third, non-adjacent track n+7 (non-adjacent to track n+1), wherein the third write operation spans servo wedges 8-11 and therefore a corresponding absolute position generated at servo wedges 8-11 is stored in the position buffer. When executing the third write operation, the difference between the absolute position stored in the position buffer for servo wedge 8 (which corresponds to writing track n+1) and the absolute position generated for the third write operation will be very large since the third track n+7 is non-adjacent with the previously written track n+1. Therefore an off-track write condition based on the absolute position stored in the position buffer will not be detected. During the fourth write operation to track n+2 as shown in FIG. 3D, an off-track write condition may be detected for servo wedges 4-5 since the absolute position stored in the position buffer corresponds to adjacent track n+1. Accordingly, in this embodiment the position buffer stores an absolute position for each servo wedge around the circumference of the disk; however, the absolute positions stored in the position buffer may correspond to different (potentially non-adjacent) tracks. A benefit provided by this embodiment is that an off-track write condition may be detected based on the absolute position of the head during the write operations without having to store the absolute position for every track written. Further, by storing the absolute position (as compared to just storing the PES for each servo wedge) in the position buffer, the case where the written tracks are non-adjacent is automatically taken into account.

In one embodiment shown in FIG. 8, the disk may be divided into a number of radial zones, wherein a separate position buffer (ABP buffer) may be maintained for each radial zone. This embodiment may improve the chances of detecting an off-track write condition since the content of each position buffer will more likely correspond to an adjacently written track. For example, in one embodiment one or more of the radial zones may correspond to a “shingled zone” wherein the tracks may be written as a circular buffer using log structured writes. In this embodiment, the tracks of a “shingled zone” are written consecutively such that the corresponding position buffer will typically comprise the absolute position information of an adjacent, previously written track. Even in radial zones where the writes may not always be consecutive, at least part of the position buffer may store absolute position information of a previously written, adjacent track such that an off-track write condition may be detected using the position buffer as described above.

In the embodiment described above, the absolute position may comprise a track address and a position error measurement based on the servo bursts in the servo wedge. In another embodiment, the absolute position may further include a head number corresponding to the disk surface being written in a multi-disk surface disk drive. In this embodiment, an off-track write condition may be detected based on the absolute position stored in the position buffer when writing to the same disk surface.

FIG. 4 is a flow diagram according to an embodiment for executing a write operation (block 42), wherein when the head reaches servo sector i (block 44) an absolute position ABPw is generated (block 46) corresponding to the servo wedge. A difference between the absolute position ABPw and the corresponding absolute position ABP[i] stored in the position buffer is compared to a threshold (block 48). If the difference is greater than the threshold, then an off-track-write condition is not detected and the absolute position ABPw is stored in the position buffer at ABP[i] (block 50). The write operation then continues (block 52) until the write operation finishes (block 54) or until an off-track write condition is detected at block 48. If it is not completed at block 54, the next servo sector is processed (increments i) and the process returns to block 44. In the embodiment of FIG. 4, when an off-track write condition is detected at block 48, the write operation is aborted (block 56). In an alternative embodiment, the absolute positions generated at block 46 may be saved in a scratch buffer, and the content of the scratch buffer copied to the position buffer after the write operation has successfully completed. This embodiment may facilitate a retry write operation when a write operation is aborted due to detecting an off-track write condition.

FIG. 5 is a flow diagram according to an embodiment which extends on the flow diagram of FIG. 4, wherein when an off-track write condition is not detected at block 48 based on the position buffer, an off-track write condition may still be detected at block 58 if the absolute position ABPw deviates sufficiently from a reference absolute position (ABRw) which corresponds to the center of the track being written. That is, if the difference between the absolute position ABPw and the reference position ABRw exceeds a threshold (block 58) an off-track write condition is detected and the write operation is aborted at block 56.

In one embodiment, the control circuitry 24 of FIG. 2A is configured to define a data buffer corresponding to a circumference of the disk. When a first write operation is executed to write first write data to a first track, the first write data is stored to a first part of the data buffer. When second write operation is executed to write second write data to a second track, at least part of the second write data is stored to a second part of the data buffer. When a third write operation is executed to write third write data to a third track, at least part of the third write data is stored to a third part of the data buffer. The data buffer simultaneously stores at least part of the first write data, the second write data, and the third write data, wherein the third track is non-adjacent to the first track. An example of this embodiment may be understood with reference to FIGS. 3A-3D described above, except that each block of the buffer corresponds to a data wedge of a write operation rather than an absolute position generated for each servo wedge.

FIG. 6 is a flow diagram illustrating this embodiment which extends on the flow diagram of FIG. 5, wherein when executing a write operation the write data written to a data wedge of the track is stored in a data buffer (block 60) similar to storing the absolute position information in the position buffer at block 50. When writing data to different data tracks, the write data overwrites the previously stored write data in the data buffer at block 60. Accordingly, the data buffer may store data wedges for different tracks, including for non-adjacent tracks. In this manner, when an off-track write condition is detected at block 48 based on the position buffer when writing to a current track, the write data stored in the data buffer may be used to refresh the data written to a previously written, adjacent track (block 62). When an off-track write condition is detected at block 58 based on the absolute reference position, the write operation is aborted (block 64) without refreshing a previously written, adjacent track since the data stored in the data buffer does not correspond to a previously written, adjacent track.

FIG. 8 illustrates an embodiment wherein the control circuitry may maintain a data buffer for each radial zone similar to maintaining a position buffer for each radial zone. Accordingly, if an off-track write condition is detected based on the position buffer for a radial zone, the corresponding data buffer may be used to refresh the data written in the previously written, adjacent track before retrying the current write operation to the current track.

FIG. 7 is a flow diagram illustrating an embodiment which extends on the flow diagram of FIG. 6, wherein when an off-track write condition is not detected at block 48 based on the position buffer, and an off-track write condition is not detected at block 58 based on the absolute reference position ABRw, an off-track write condition may still be predicted at block 66. In this embodiment, a predicted absolute position (ABPpw) corresponding to a next servo wedge is generated using any suitable algorithm. For example, in one embodiment the predicted absolute position is generated based on:
ABPpw(k)=2·ABPw(k)−ABPw(k−1)
If a difference between the ABPpw and the absolute position stored in the position buffer APB[i+1] for the next servo wedge exceeds a threshold at block 66, an off-track write condition is detected. In one embodiment, when an off-track write condition is detected based on the predicted absolute position of a next servo wedge, the write operation is aborted at block 64 without refreshing the data of the previously written, adjacent track.

FIG. 9A shows a data storage device in the form of a disk drive according to an embodiment comprising a head 16 actuated over a disk 18, and control circuitry 24 configured to execute the flow diagram of FIG. 9B. A write throughput and a read throughput of the disk drive are measured for a plurality of different off-track write thresholds (block 67). An operating off-track write threshold is selected based on the measurements (block 68), and a write operation to the disk is aborted based on the operating off-track write threshold (block 70).

FIG. 10 shows an example of this embodiment wherein the write throughput of the disk drive increases as the off-track write threshold increases since there are fewer off-track write conditions detected and fewer write aborts. However, increasing the off-track write threshold eventually causes the read throughput of the disk drive to decrease since the reliability of the recorded data decreases which increases the data recovery time due, for example, to executing more retry reads and/or other heroic error recovery procedures. In one embodiment, the control circuitry 24 is configured to select the operating off-track write threshold that substantially maximizes the write throughput biased by a first weighting and the read throughput biased by a second weighting. For example, in one embodiment the control circuitry 24 is configured to select the operating off-track write threshold as the minimum of the measured off-track write thresholds that substantially maximizes the write throughput biased by a first weighting and the read throughput biased by a second weighting. Any suitable first weighting and second weighting may be selected to bias the write/read throughputs, for example, to achieve a target ratio between the write/read throughputs. For example, in one embodiment the first weighting may be different than the second weighting so that the disk drive exhibits better read throughput performance as compared to write throughput.

Any suitable operating off-track write threshold may be calibrated by executing the flow diagram of FIG. 9B, such as the position buffer threshold at block 48 of FIG. 7, the absolute reference position ABRw threshold at block 58 of FIG. 7, and/or the predictive threshold at block 66 of FIG. 7. In one embodiment, two or more off-track write thresholds may be calibrated relative to the write/read throughput of the disk drive.

Any suitable control circuitry may be employed to implement the flow diagrams in the above embodiments, such as any suitable integrated circuit or circuits. For example, the control circuitry may be implemented within a read channel integrated circuit, or in a component separate from the read channel, such as a disk controller, or certain operations described above may be performed by a read channel and others by a disk controller. In one embodiment, the read channel and disk controller are implemented as separate integrated circuits, and in an alternative embodiment they are fabricated into a single integrated circuit or system on a chip (SOC). In addition, the control circuitry may include a suitable preamp circuit implemented as a separate integrated circuit, integrated into the read channel or disk controller circuit, or integrated into a SOC.

In one embodiment, the control circuitry comprises a microprocessor executing instructions, the instructions being operable to cause the microprocessor to perform the flow diagrams described herein. The instructions may be stored in any computer-readable medium. In one embodiment, they may be stored on a non-volatile semiconductor memory external to the microprocessor, or integrated with the microprocessor in a SOC. In another embodiment, the instructions are stored on the disk and read into a volatile semiconductor memory when the disk drive is powered on. In yet another embodiment, the control circuitry comprises suitable logic circuitry, such as state machine circuitry.

In various embodiments, a disk drive may include a magnetic disk drive, an optical disk drive, etc. In addition, while the above examples concern a disk drive, the various embodiments are not limited to a disk drive and can be applied to other data storage devices and systems, such as magnetic tape drives, solid state drives, hybrid drives, etc. In addition, some embodiments may include electronic devices such as computing devices, data server devices, media content storage devices, etc. that comprise the storage media and/or control circuitry as described above.

The various features and processes described above may be used independently of one another, or may be combined in various ways. All possible combinations and subcombinations are intended to fall within the scope of this disclosure. In addition, certain method, event or process blocks may be omitted in some implementations. The methods and processes described herein are also not limited to any particular sequence, and the blocks or states relating thereto can be performed in other sequences that are appropriate. For example, described tasks or events may be performed in an order other than that specifically disclosed, or multiple may be combined in a single block or state. The example tasks or events may be performed in serial, in parallel, or in some other manner. Tasks or events may be added to or removed from the disclosed example embodiments. The example systems and components described herein may be configured differently than described. For example, elements may be added to, removed from, or rearranged compared to the disclosed example embodiments.

While certain example embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions disclosed herein. Thus, nothing in the foregoing description is intended to imply that any particular feature, characteristic, step, module, or block is necessary or indispensable. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the embodiments disclosed herein.

Claims (28)

What is claimed is:
1. A data storage device comprising:
a disk comprising a plurality of tracks defined by servo sectors, wherein each servo sector comprises a plurality of servo bursts and the servo sectors define a plurality of servo wedges;
a head actuated over the disk; and
control circuitry configured to:
execute a first write operation to a first track and generate a first absolute position for the head corresponding to a first servo wedge;
execute a second write operation to a second track and generate a second absolute position for the head corresponding to the first servo wedge; and
detect an off-track write condition when executing the second write operation based on the first absolute position and the second absolute position;
wherein the first absolute position comprises a track address of the first track and a position error measurement based on the servo bursts in the first servo wedge.
2. The data storage device as recited in claim 1, wherein the first absolute position comprises a head number representing the head.
3. The data storage device as recited in claim 1, wherein the control circuitry is further configured to abort the second write operation when the off-track write condition is detected.
4. The data storage device as recited in claim 1, wherein for a first radial zone of the disk comprising the first track and the second track the control circuitry is further configured to save an absolute position corresponding to each servo wedge, wherein at least one of the saved absolute positions corresponds to the first write operation and at least one of the saved absolute positions corresponds to the second write operation.
5. The data storage device as recited in claim 4, wherein at least one of the saved absolute positions corresponds to a third write operation to a third track non-adjacent to the first track.
6. The data storage device as recited in claim 4, wherein for a second radial zone of the disk comprising a third track and a fourth track, the control circuitry is further configured to save an absolute position corresponding to each servo wedge, wherein at least one of the saved absolute positions corresponds to a third write operation to the third track and at least one saved absolute positions corresponds to a fourth write operation to the fourth track.
7. A data storage device comprising:
a disk comprising a plurality of tracks defined by servo sectors;
a head actuated over the disk; and
control circuitry configured to:
define a first data buffer corresponding to a first circumference of the disk;
execute a first write operation to write first write data to a first track and store the first write data to a first part of the first data buffer;
execute a second write operation to write second write data to a second track and store at least part of the second write data to a second part of the first data buffer; and
execute a third write operation to write third write data to a third track and store at least part of the third write data to a third part of the first data buffer;
wherein:
the first data buffer simultaneously stores at least part of the first write data, the second write data, and the third write data; and
the third track is non-adjacent to the first track.
8. The data storage device as recited in claim 7, wherein the control circuitry is further configured to overwrite at least part of the first write data saved in the first data buffer with at least part of the third write data.
9. The data storage device as recited in claim 7, wherein the first circumference of the disk is within a first radial zone of the disk and the control circuitry is further configured to:
define a second data buffer corresponding to a second circumference of the disk within a second radial zone of the disk; and
save write data in the second data buffer for write operations to the tracks in the second radial zone.
10. The data storage device as recited in claim 7, wherein the control circuitry is further configured to:
detect an off-track write condition when executing the second write operation; and
when the off-track write condition is detected, rewrite at least part of the first write data saved in the first data buffer to the first track.
11. A data storage device comprising:
a disk;
a head actuated over the disk; and
control circuitry configured to:
measure a write throughput and a read throughput for a plurality of different off-track write thresholds;
select an operating off-track write threshold based on the measurements; and
abort a write operation to the disk based on the operating off-track write threshold.
12. The data storage device as recited in claim 11, wherein the control circuitry is further configured to select the operating off-track write threshold that substantially maximizes the write throughput biased by a first weighting and the read throughput biased by a second weighting.
13. The data storage device as recited in claim 11, wherein the control circuitry is further configured to select the operating off-track write threshold as the minimum of the measured off-track write thresholds that substantially maximizes the write throughput biased by a first weighting and the read throughput biased by a second weighting.
14. The data storage device as recited in claim 11, wherein:
the write throughput increases when the off-track write threshold increases; and
the read throughput decreases when the off-track write threshold increases.
15. A method of operating a data storage device, the method comprising:
executing a first write operation to a first track on a disk using a head and generating a first absolute position for the head corresponding to a first servo wedge on the disk;
executing a second write operation to a second track and generating a second absolute position for the head corresponding to the first servo wedge; and
detecting an off-track write condition when executing the second write operation based on the first absolute position and the second absolute position;
wherein the first absolute position comprises a track address of the first track and a position error measurement based on servo bursts in the first servo wedge.
16. The method as recited in claim 15, wherein the first absolute position comprises a head number representing the head.
17. The method as recited in claim 15, wherein the method further comprises aborting the second write operation when the off-track write condition is detected.
18. The method as recited in claim 15, wherein for a first radial zone of the disk comprising the first track and the second track the method further comprises saving an absolute position corresponding to each servo wedge, wherein at least one of the saved absolute positions corresponds to the first write operation and at least one of the saved absolute positions corresponds to the second write operation.
19. The method as recited in claim 18, wherein at least one of the saved absolute positions corresponds to a third write operation to a third track non-adjacent to the first track.
20. The method as recited in claim 18, further comprising, for a second radial zone of the disk comprising a third track and a fourth track, saving an absolute position corresponding to each servo wedge, wherein at least one of the saved absolute positions corresponds to a third write operation to the third track and at least one saved absolute positions corresponds to a fourth write operation to the fourth track.
21. A method of operating a data storage device, the method comprising:
defining a first data buffer corresponding to a first circumference of a disk;
executing a first write operation to write first write data to a first track on the disk and storing the first write data to a first part of the first data buffer;
executing a second write operation to write second write data to a second track on the disk and storing at least part of the second write data to a second part of the first data buffer; and
executing a third write operation to write third write data to a third track on the disk and store at least part of the third write data to a third part of the first data buffer;
wherein:
the first data buffer simultaneously stores at least part of the first write data, the second write data, and the third write data; and
the third track is non-adjacent to the first track.
22. The method as recited in claim 21, further comprising overwriting at least part of the first write data saved in the first data buffer with at least part of the third write data.
23. The method as recited in claim 21, wherein the first circumference of the disk is within a first radial zone of the disk and the method further comprises:
defining a second data buffer corresponding to a second circumference of the disk within a second radial zone of the disk; and
saving write data in the second data buffer for write operations to the tracks in the second radial zone.
24. The method as recited in claim 21, further comprising:
detecting an off-track write condition when executing the second write operation; and
when the off-track write condition is detected, rewriting at least part of the first write data saved in the first data buffer to the first track.
25. A method of operating a data storage device, the method comprising:
measuring a write throughput and a read throughput for a plurality of different off-track write thresholds;
selecting an operating off-track write threshold based on the measurements; and
aborting a write operation to a disk based on the operating off-track write threshold.
26. The method as recited in claim 25, further comprising selecting the operating off-track write threshold that substantially maximizes the write throughput biased by a first weighting and the read throughput biased by a second weighting.
27. The method as recited in claim 25, further comprising selecting the operating off-track write threshold as the minimum of the measured off-track write thresholds that substantially maximizes the write throughput biased by a first weighting and the read throughput biased by a second weighting.
28. The method recited in claim 25, wherein:
the write throughput increases when the off-track write threshold increases; and
the read throughput decreases when the off-track write threshold increases.
US14538610 2014-11-11 2014-11-11 Data storage device saving absolute position at each servo wedge for previous write operations Active US9355667B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US14538610 US9355667B1 (en) 2014-11-11 2014-11-11 Data storage device saving absolute position at each servo wedge for previous write operations

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US14538610 US9355667B1 (en) 2014-11-11 2014-11-11 Data storage device saving absolute position at each servo wedge for previous write operations

Publications (1)

Publication Number Publication Date
US9355667B1 true US9355667B1 (en) 2016-05-31

Family

ID=56027894

Family Applications (1)

Application Number Title Priority Date Filing Date
US14538610 Active US9355667B1 (en) 2014-11-11 2014-11-11 Data storage device saving absolute position at each servo wedge for previous write operations

Country Status (1)

Country Link
US (1) US9355667B1 (en)

Citations (338)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6181493B2 (en)
US6014283A (en) 1997-05-15 2000-01-11 Western Digital Corporation Non-quadrature servo burst pattern for micro-jogging a magnetoresistive head in a magnetic disk drive
US6052250A (en) 1997-08-25 2000-04-18 Western Digital Corporation Disk drive with separately determined servo and data track pitch
US6052076A (en) 1998-10-14 2000-04-18 Western Digital Corporation Digital-to-analog converter having high resolution and high bandwidth
US6067206A (en) 1997-11-18 2000-05-23 Western Digital Corporation Method and apparatus to compensate for servo wedge rotational offset after a head switch
US6078453A (en) 1997-11-12 2000-06-20 Western Digital Corporation Method and apparatus for optimizing the servo read channel of a hard disk drive
US6091564A (en) 1998-04-30 2000-07-18 Western Digital Corporation Disk drive with calibration bursts that are recorded on a spiral and method of recording the same
US6094020A (en) 1998-11-18 2000-07-25 Western Digital Corporation Disk drive utilizing Bemf of spindle motor to increase VCM voltage during seeks
US6101065A (en) 1998-03-30 2000-08-08 Western Digital Corporation Disk drive with seek profile selection based on read/write operation
US6104153A (en) 1999-02-23 2000-08-15 Western Digital Corporation Disk drive employing method of spinning down its spindle motor to reduce the time required for spinning it down and subsequently spinning it up
US6111714A (en) * 1997-03-27 2000-08-29 International Business Machines Corporation Disk drive and write control method for a disk drive
US6122135A (en) 1997-12-19 2000-09-19 Western Digital Corporation Disk drive with voice coil motor rise time manager
US6122133A (en) 1998-06-17 2000-09-19 Western Digital Corporation Hybrid method of determining a fractional track position of a read transducer in a hard disk drive
US6141175A (en) 1997-10-08 2000-10-31 Western Digital Corporation Repeatable runout cancellation in sectored servo disk drive positioning system
US6160368A (en) 1998-06-22 2000-12-12 Western Digital Corporation Faster spin-down operation in a disk drive by utilizing pulsed braking
US6181493B1 (en) 1998-06-05 2001-01-30 Seagate Technology Llc Write fault thresholds adaptive by head and disc location in a disc drive
US6181502B1 (en) 1998-07-01 2001-01-30 Western Digital Corporation Faster access time in a disk drive by utilizing increased VCM potential voltage
US6195222B1 (en) 1998-11-04 2001-02-27 Western Digital Corporation Disk drive with seek profile selection based on a queued vs. non-queued environment
US6198590B1 (en) 1998-07-21 2001-03-06 Western Digital Corporation Disk drive employing method of spinning down its spindle motor to reduce the time required for subsequently spinning it up
US6198584B1 (en) 1998-04-30 2001-03-06 Western Digital Corporation Disk drive with staggered calibration bursts that are disposably located in data regions and method of using the same for calibrating a read head
US6204988B1 (en) 1998-08-24 2001-03-20 Western Digital Corporation Disk drive capable of autonomously evaluating and adapting the frequency response of its servo control system
US6215608B1 (en) 1998-08-31 2001-04-10 International Business Machines Corporation Hardware inhibit for a disk drive digital servo control system
US6243223B1 (en) 1998-01-15 2001-06-05 Western Digital Corporation Disk drive with servo burst phasing for improved linearity and off-track performance with a wide reading transducer
US6281652B1 (en) 2000-03-24 2001-08-28 Western Digital Corporation Method of using two low-resolution DACS for converting high-resolution digital demands into analog output signals that monotonically drive an actuator motor in a disk drive
US6285521B1 (en) 1999-03-25 2001-09-04 Western Digital Technologies, Inc. Disk drive employing power source modulation for reducing power consumption
US6292320B1 (en) 1998-03-23 2001-09-18 Western Digital Technologies, Inc. Disk drive with dual stage actuator radial offset calibration
US6320718B1 (en) 1999-01-07 2001-11-20 Western Digital Technologies, Inc. Disk drive with zero read offset in reserved area and method of making same
US6342984B1 (en) 1998-07-01 2002-01-29 Western Digital Technologies, Inc Disk drive including DC to DC voltage converter for increasing voltage to its spindle motor and VCM
US6347018B1 (en) 1990-09-18 2002-02-12 Rodime Plc Digital servo control system for use in disk drives
US6369974B1 (en) 1999-02-09 2002-04-09 Western Digital Technologies, Inc. Disk drive with method of constructing a continuous position signal and constrained method of linearizing such position signal while maintaining continuity
US6369972B1 (en) 1999-05-14 2002-04-09 Western Digital Technologies, Inc. Temperature monitoring method of a disk drive voice coil motor from a traveled distance
US6421197B1 (en) 1999-02-22 2002-07-16 Seagate Technology Llc Optimal reader/writer offsets and write fault thresholds in a disc drive
US6462896B1 (en) 2000-11-30 2002-10-08 Western Digital Technologies, Inc. Method for minimizing adjacent track data loss during a write operation in a disk drive
US6476996B1 (en) 2000-02-15 2002-11-05 Western Digital Technologies, Inc. Disk drive comprising an actuator driver circuit for retracting a head independent of a servo microprocessor when a spindle speed fault mode is detected
US6484577B1 (en) 2001-10-31 2002-11-26 Western Digital Technologies, Inc. Accelerometer signal processor comprising variable oscillators and counters
US6493169B1 (en) 2000-04-19 2002-12-10 Western Digital Technologies, Inc. Disk drive employing spindle motor commutation time variation for reducing acoustic noise
US6496324B1 (en) 1999-06-29 2002-12-17 Western Digital Technologies, Inc. Disk drive employing method of unlatching actuator arm using VCM voltage limiting circuit to limit actuator arm velocity
US6496320B1 (en) 2000-02-09 2002-12-17 Seagate Technology Llc Adaptive attenuation of multi-axis vibrational disturbance
US6498698B1 (en) 1999-06-29 2002-12-24 Western Digital Technologies, Inc. Servowriter employing method of unlatching actuator arm using VCM voltage limiting circuit to limit actuator arm velocity
US6507450B1 (en) 1999-06-11 2003-01-14 Western Digital Technologies, Inc. Method of continuously recording servo bursts along one continuous, single helix spiral
US6534936B2 (en) 2000-04-28 2003-03-18 Western Digital Technologies, Inc. Disk drive employing method of spinning up spindle motor including detecting BEMF polarity change for selecting initial commutation state
US6538839B1 (en) 2001-01-31 2003-03-25 Western Digital Technologies, Inc. Disk drive employing adaptive feed-forward vibration compensation to enhance a retry operation
US6545835B1 (en) 2000-08-31 2003-04-08 Western Digital Technologies, Inc. Method and apparatus for RRO learning before and after shipping to cancel RRO in a disk drive
US6549359B1 (en) 2000-04-19 2003-04-15 Western Digital Technologies, Inc. Disk drive comprising spin down circuitry having a current limit circuit for enhancing power and braking control
US6560056B1 (en) 2001-01-31 2003-05-06 Western Digital Technologies, Inc. Disk drive comprising a motor driver IC employing a serial interface for initiating the transmission of real-time status data to a controller IC
US6574062B1 (en) 2000-04-19 2003-06-03 Western Digital Technologies, Inc. Disk drive comprising a demand limit circuit for enhancing power management during spin down
US6614618B1 (en) 2000-03-31 2003-09-02 Western Digital Technologies, Inc. Disk drive with feed-forward control path that receives a reference position signal to apply a feed-forward command effort at a rate greater than a servo sampling rate
US6614615B1 (en) 2000-03-31 2003-09-02 Western Digital Technologies, Inc. Disk drive with adaptive control path that produces an adaptive control effort based on a characterized deviation between actual and modeled plant response
US6636377B1 (en) 2000-06-30 2003-10-21 Western Digital Technologies, Inc. Method of tuning feed-forward control in a disk drive
US6690536B1 (en) 2000-10-31 2004-02-10 Western Digital Technologies, Inc. Disk drive employing VCM demand current to calibrate VCM IR voltage for velocity control of an actuator arm
US6693764B1 (en) 2001-01-31 2004-02-17 Western Digital Technologies, Inc. Method and disk drive for improving head position accuracy during track following through real-time identification of external vibration
US6707635B1 (en) 2000-10-05 2004-03-16 Western Digital Technologies, Inc. Method and apparatus for RRO learning on alternate tracks before and after shipping to cancel RRO in a disk drive
US6710966B1 (en) 2001-10-23 2004-03-23 Western Digital Technologies, Inc. Method for reducing an effect of vibration on a disk drive during a track following operation by adjusting an adaptive-filter gain applied to an acceleration sensor signal
US6710953B1 (en) 2001-03-30 2004-03-23 Western Digital Technologies, Inc. Method and disk drive for improving data storage capacity of data tracks using push-down wedges
US6714372B1 (en) 2001-09-28 2004-03-30 Western Digital Technologies, Inc. Method of manufacturing a disk drive by measuring the read width in the servo-writer to set the write unsafe limit
US6714371B1 (en) 2001-08-31 2004-03-30 Western Digital Technologies, Inc. Method and disk drive for shock estimation and write termination control
US6717757B1 (en) 2000-05-25 2004-04-06 Maxtor Corporation Variable write fault protection window
US6724564B1 (en) 2000-11-30 2004-04-20 Western Digital Technologies, Inc. Seek distance dependent variable max VCM seek current to control thermal rise in VCM's
US6731450B1 (en) 2000-11-30 2004-05-04 Western Digital Technologies, Inc. Disk drive control system and method for determining the temperature of an actuator coil
US6735033B1 (en) 2001-12-10 2004-05-11 Western Digital Technologies, Inc. Method for recovering from shock events occurring to a disk drive during data write operations to improve data reliability
US6735041B1 (en) 2002-03-29 2004-05-11 Western Digital Technologies, Inc. Method for seeking in a magnetic disk drive having a spiral track
US6738220B1 (en) 2001-09-28 2004-05-18 Western Digital Technologies, Inc. Servo settling by utilization of a bias torque offset value which depends on the memory of previous seek operations
US6747837B1 (en) 2001-08-31 2004-06-08 Western Digital Technologies, Inc. Disk drive comprising an integrator for controlling a VCM actuator and transformer for controlling a piezoelectric actuator
US20040109253A1 (en) 2002-12-09 2004-06-10 Hitachi Global Storage Technologies Japan, Ltd. Magnetic recording disk drive and method for ensuring magnetic recording function thereof
US6760186B1 (en) 2000-11-30 2004-07-06 Western Digital Technologies, Inc. Disk drive having first-written servo wedge marked and method for forming marked servo wedges
US6781780B1 (en) * 2001-06-21 2004-08-24 Western Digital Technologies, Inc. Method and system for preventing data loss from an off-track write condition in a disk drive by rewriting data buffered from an adjacent track
US6788483B1 (en) 2001-08-31 2004-09-07 Western Digital Technologies, Inc. Disk drive comprising a programmable inverting voltage regulator configured relative to the disk drive's mode of operation
US6791785B1 (en) 2001-02-28 2004-09-14 Western Digital Technologies, Inc. Disk drive with efficient coil temperature estimation
US6795262B1 (en) 2002-06-28 2004-09-21 Western Digital Technologies, Inc. Method of modifying on-track declaration algorithm of a disk drive based upon detection of external vibration condition
US6795268B1 (en) 2000-10-31 2004-09-21 Western Digital Technologies, Inc. Disk drive employing seek time vcm ir voltage calibration for velocity control of an actuator arm
US6819518B1 (en) 2002-10-24 2004-11-16 Western Digital Technologies, Inc. Method and apparatus for self servowriting of tracks of a disk drive using a servo control loop having a two-dimensional digital state compensator
US6826007B1 (en) 2002-08-30 2004-11-30 Western Digital Technologies, Inc. Disk drive using dual slope integrator to extract velocity of an actuator arm from a back EMF voltage
US6826006B1 (en) 2002-09-30 2004-11-30 Western Digital Technologies, Inc. Method for recursively determining repeatable runout cancellation values in a magnetic disk drive
US6847502B1 (en) 2002-06-28 2005-01-25 Western Digital Technologies, Inc. Repeatable runout determination within a rotating media storage device
US6850384B1 (en) 2003-02-28 2005-02-01 Western Digital Technologies, Inc. Disk drive comprising oscillators and counters for sensing current in a voice coil motor
US6850383B1 (en) 2003-02-28 2005-02-01 Western Digital Technologies, Inc. Disk drive comprising current sense circuitry for a voice coil motor
US6867944B1 (en) 2000-10-31 2005-03-15 Western Digital Technologies, Inc. Disk drive comprising VCM stall detector for velocity control of an actuator arm
US6876508B1 (en) 2002-07-31 2005-04-05 Western Digital Technologies, Inc. Disk drive comprising control circuitry powered by a secondary voltage supplied by a center tap of a spindle motor during a normal operating mode
US6882489B1 (en) * 2000-08-15 2005-04-19 Maxtor Corporation Dynamic off-track detector
US6882496B1 (en) 2003-05-30 2005-04-19 Western Digital Technologies, Inc. Method for adaptively allocating data storage tracks in a disk drive to improve seek performance
US6885514B1 (en) 2001-07-31 2005-04-26 Western Digital Technologies, Inc. Method of manufacturing and disk drive produced by measuring the read and write widths and varying the track pitch in the servo-writer
US6900958B1 (en) 2003-07-31 2005-05-31 Western Digital Technologies, Inc. Method and disk drive for improving head position accuracy during track following through real-time identification of external vibration and monitoring of write-unsafe occurrences
US6900959B1 (en) 2003-03-31 2005-05-31 Western Digital Technologies, Inc. Disk drive comprising an offset-nulling amplifier for detecting a back EMF voltage of a voice coil motor
US6903897B1 (en) 2003-06-27 2005-06-07 Western Digital Technologies, Inc. Performance of a rotary actuator in a disk drive
US6914740B1 (en) 2003-11-26 2005-07-05 Western Digital Technologies, Inc. Disk drive employing BEMF spindle speed control or wedge spindle speed control
US6914743B1 (en) 2000-11-30 2005-07-05 Western Digital Technologies, Inc. Vibration cancellation in a disk drive by using an acceleration sensor and adaptively adjusting its gain to minimize external acceleration effects
US6920004B1 (en) 2002-03-29 2005-07-19 Western Digital Technologies, Inc. Method for adjusting a delay time for opening a servo sector detection window in a disk drive having a spiral track
US6924959B1 (en) 2003-08-29 2005-08-02 Western Digital Technologies, Inc. Reducing estimation period for repeatable runout errors in a disk drive
US6924960B1 (en) 2003-07-31 2005-08-02 Western Digital Technologies, Inc. Timing compensation in a self-servowriting system
US6924961B1 (en) 2002-08-30 2005-08-02 Western Digital Technologies, Inc. Method and apparatus for self servowriting of tracks of a disk drive using an observer based on an equivalent one-dimensional state model
US6934114B1 (en) 2002-10-24 2005-08-23 Western Digital Technologies, Inc. Reduced bit number wedge identification techniques within a rotating media storage device
US6934135B1 (en) 2003-02-28 2005-08-23 Western Digital Technologies, Inc. Disk drive monitoring a supply current to protect motor driver circuits
US6937420B1 (en) 2004-05-28 2005-08-30 Western Digital Technologies, Inc. Determining repeatable runout cancellation information using PES information generated during self servo-writing operations
US6937423B1 (en) 2004-02-06 2005-08-30 Western Digital Technologies, Inc. Reducing effects of rotational vibration in disk drive
US6940679B1 (en) 2000-11-07 2005-09-06 Maxtor Corporation Method and apparatus for increasing track density by adapting write fault gate to position error signal as it varies from ID to OD
US6952322B1 (en) 2002-11-27 2005-10-04 Western Digital Technologies, Inc. Disk drive reading servo sectors recorded at a relative offset on multiple disk surfaces to increase the servo sample rate
US6954324B1 (en) 2003-11-26 2005-10-11 Western Digital Technologies, Inc. Disk drive disabling BEMF detection window to reduce acoustic noise while using wedge spindle speed control
US6958881B1 (en) 2003-11-26 2005-10-25 Western Digital Technologies, Inc. Disk drive control system having a servo processing accelerator circuit
US6963465B1 (en) 2004-06-29 2005-11-08 Western Digital Technologies, Inc. Method for preventing radial error propagation during self-servowriting of tracks in a magnetic disk drive
US6965488B1 (en) 2003-06-27 2005-11-15 Western Digital Technologies, Inc. Disk drive controlling ripple current of a voice coil motor when driven by a PWM driver
US6967458B1 (en) 2002-07-31 2005-11-22 Western Digital Technologies, Inc. Decreasing spin up time in a disk drive by adjusting a duty cycle of a spindle motor PWM signal to maintain constant average input current
US6967811B1 (en) 2004-07-02 2005-11-22 Western Digital Technologies, Inc. Disk drive having first and second seek operating modes for controlling voice coil motor temperature rise
US6968422B1 (en) 2003-06-27 2005-11-22 Western Digital Technologies, Inc. Disk drive employing a modified rotational position optimization algorithm to account for external vibrations
US6970319B1 (en) 2003-05-27 2005-11-29 Western Digital Technologies, Inc. Disk drive comprising a pulse width modulated demand limit circuit for enhancing power management during spin-down
US6972922B1 (en) 2003-02-07 2005-12-06 Western Digital Technologies, Inc. Disk drive having internal data structures for efficiently storing repeatable runout cancellation information
US6972540B1 (en) 2004-11-19 2005-12-06 Western Digital Technologies, Inc. Disk drive employing wedge spindle speed control with eccentricity compensation
US6972539B1 (en) 2003-04-30 2005-12-06 Western Digital Technologies, Inc. Disk drive employing commutation phase modulation and current modulation of a spindle motor
US6975480B1 (en) 2002-04-17 2005-12-13 Western Digital Technologies, Inc. Method for determining repeatable runout cancellation values in a magnetic disk drive using filtering
US6975468B1 (en) * 2001-02-16 2005-12-13 Maxtor Corporation Method to accurately predict hard error rates resulting from encroachment
US6977789B1 (en) 2002-01-31 2005-12-20 Western Digital Technologies, Inc. Disk drive for circular self servo writing and spiral self servo writing using prewritten reference servo bursts
US6980389B1 (en) 2004-02-27 2005-12-27 Western Digital Technologies, Inc. Disk drive having a disk including a servo burst pattern having a normal servo burst field and a quadrature servo burst field
US6987636B1 (en) 2004-09-17 2006-01-17 Western Digital Technologies, Inc. Adjusting track density over disk radius by changing slope of spiral tracks used to servo write a disk drive
US6987639B1 (en) 2003-09-30 2006-01-17 Western Digital Technologies, Inc. Disk drive modifying a rotational position optimization algorithm based on motor capability of a VCM
US6989954B1 (en) 2004-01-31 2006-01-24 Western Digital Technologies, Inc. Demodulating servo sectors and spiral tracks using common circuitry
US6992851B1 (en) 2004-06-30 2006-01-31 Western Digital Technologies, Inc. Method for nonsequentially writing reference spiral servo patterns to a disk to compensate for disk expansion
US6992848B1 (en) 2002-03-29 2006-01-31 Western Digital Technologies, Inc. Using an external spiral servo writer to write spiral reference patterns to a disk to facilitate writing product servo bursts to the disk
US6992852B1 (en) 2004-10-15 2006-01-31 Western Digital Technologies, Inc. Method for reducing disk thermal expansion effects while writing reference spiral servo patterns to a disk of a disk drive
US6995941B1 (en) 2005-01-07 2006-02-07 Western Digital Technologies, Inc. Method for improving head position determination in a disk drive
US6999263B1 (en) 2003-10-24 2006-02-14 Western Digital Technologies, Inc. Method and apparatus for self servowriting of tracks of a disk drive using a servo control loop having a two-dimensional weighted digital state compensator
US6999267B1 (en) 2004-04-28 2006-02-14 Western Digital Technologies, Inc. Method for iteratively determining repeatable runout cancellation values in a magnetic disk drive
US7006320B1 (en) 2002-07-31 2006-02-28 Western Digital Technologies, Inc. Disk drive comprising a multi-phase spindle motor having a center tap connectable to a secondary supply voltage
US7016134B1 (en) 2004-01-31 2006-03-21 Western Digital Technologies, Inc. Using an external spiral servo writer to write spiral tracks to a disk to facilitate writing product servo sectors to the disk
US7023640B1 (en) 2004-05-27 2006-04-04 Western Digital Technologies, Inc. Acceleration disturbance detection subsystem for use with disk drives
US7023637B1 (en) 2004-06-01 2006-04-04 Western Digital Technologies, Inc. Disk drive having a disk including a servo burst pattern that improves the signal to noise ratio during track following for writing
US7027257B1 (en) 2004-04-01 2006-04-11 Western Digital Technologies, Inc. Disk drive having a disk including a servo burst pattern in which a phase difference between radially adjacent servo bursts is less than 180 degrees
US7027256B1 (en) 2003-02-28 2006-04-11 Western Digital Technologies, Inc. Disk drive having servo sectors that store repeatable runout correction values and related error correction code data
US7050258B1 (en) 2002-12-24 2006-05-23 Western Digital Technologies, Inc. Disk drive and method for improved disk rotation control
US7050249B1 (en) 2002-12-24 2006-05-23 Western Digital Technologies, Inc. System and method for processing track identification data in a disk drive
US7050254B1 (en) 2005-02-11 2006-05-23 Western Digital Technologies, Inc. Internal disk drive temperature estimation
US7054098B1 (en) 2004-06-01 2006-05-30 Western Digital Technologies, Inc. Disk drive employing asymmetric acceleration/deceleration pulses for acoustic noise reduction during unlatch
US7061714B1 (en) 2003-12-19 2006-06-13 Western Digital Technologies, Inc. Disk drive modifying estimated seek times for a rotational position optimization algorithm based on change in estimated seek time parameter
US7064918B1 (en) 2003-10-31 2006-06-20 Western Digital Technologies, Inc. Reducing head gain calibration time in a disk drive
US7068463B1 (en) 2004-06-14 2006-06-27 Western Digital Technologies, Inc. Disk drive employing a velocity profile and back EMF feedback to control a voice coil motor
US7068459B1 (en) 2004-09-20 2006-06-27 Western Digital Technologies, Inc. Adjusting track density by changing PES algorithm when servo writing a disk drive from spiral tracks
US7068451B1 (en) 2004-11-16 2006-06-27 Western Digital Technologies, Inc. Disk drive estimating a sinusoidal error in a wedge time period due to eccentricity in disk rotation
US7068461B1 (en) 2004-11-29 2006-06-27 Western Digital Technologies, Inc. Servo writing a disk drive by overwriting a harmonic frequency fill pattern in the servo burst area
US7088547B1 (en) 2005-07-25 2006-08-08 Western Digital Technologies, Inc. Disk drive recursively estimating repeatable runout
US7095579B1 (en) 2005-06-02 2006-08-22 Western Digital Technologies, Inc. Disk drive employing momentum based unload during power failure
US7097110B2 (en) 2003-09-02 2006-08-29 Texas Instruments Incorporated Temperature compensation systems and methods for use with read/write heads in magnetic storage devices
US7110214B1 (en) 2005-01-18 2006-09-19 Western Digital Technologies, Inc. Disk drive to implement a seek operation utilizing a deceleration velocity profile that mathematically models BEMFs
US7110208B1 (en) 2004-07-30 2006-09-19 Western Digital Technologies, Inc. Method for improving servo performance in a disk drive having tracks with mini servo wedges
US7113365B1 (en) 2002-12-24 2006-09-26 Western Digital Technologies, Inc. Disk drive comprising a spindle motor having a windings shield for reduced disk voltage coupling
US7116505B1 (en) 2003-09-30 2006-10-03 Western Digital Technologies, Inc. Reducing the length of servo-wedges in a disk drive
US7126781B1 (en) 2003-02-28 2006-10-24 Western Digital Technologies, Inc. Disk drive employing a multi-stage pulse width modulated voice coil motor driver
US7158329B1 (en) 2005-05-23 2007-01-02 Western Digital Technologies, Inc. Disk drive employing active braking using inductive sense
US7180703B1 (en) 2004-05-15 2007-02-20 Western Digital Technologies, Inc. Disk drive comprising a spindle motor employing anionic/cationic lubricant to reduce disk surface potential
US7184230B1 (en) 2002-06-01 2007-02-27 Western Digital Technologies, Inc. System and method for processing track identifier errors to mitigate head instability in data storage devices
US7196864B1 (en) 2005-06-15 2007-03-27 Western Digital Technologies, Inc. Disk drive having a servo control system optimized for faster determination of repeatable runout correction values and related method
US7199966B1 (en) 2005-06-28 2007-04-03 Western Digital Technologies, Inc. Disk drive adjusting seek profile for variable seek times to reduce power dissipation
US7203021B1 (en) 2005-11-15 2007-04-10 Western Digital Technologies, Inc. Self-heating disk drive
US7209305B2 (en) 2005-01-06 2007-04-24 Hitachi Global Storage Technologies Netherlands, B.V. Method for determining unique write inhibit thresholds for individual heads for maximizing file servo performance
US7209321B1 (en) 2003-07-31 2007-04-24 Western Digital Technologies, Inc. Disk drive pulse width modulating a voice coil motor using model reference current feedback
US7212364B1 (en) 2004-01-31 2007-05-01 Western Digital Technologies, Inc. Servo writing a disk drive by synchronizing a servo write clock in response to a sync mark reliability metric
US7212374B1 (en) 2005-10-14 2007-05-01 Western Digital Technologies, Inc. Disk drive to characterize misaligned servo wedges
US7215504B1 (en) 2005-10-19 2007-05-08 Western Digital Technologies, Inc. Disk drive using an optical sensor to detect a position of an actuator arm
US7224546B1 (en) 2004-01-31 2007-05-29 Western Digital Technologies, Inc. Disk drive employing a calibrated brake pulse to reduce acoustic noise when latching an actuator arm
US20070139809A1 (en) 2005-12-09 2007-06-21 Maxtor Corporation Adaptive write unsafe thresholds for self servo writing
US7248426B1 (en) 2004-07-30 2007-07-24 Western Digital Technologies, Inc. Servo writing a disk drive from spiral tracks by shifting a demodulation window an integer number of sync mark intervals
US7251098B1 (en) 2004-11-19 2007-07-31 Western Digital Technologies, Inc. Disk drive adjusting write clock frequency to compensate for eccentricity in disk rotation
US7253582B1 (en) 2004-05-28 2007-08-07 Western Digital Technologies, Inc. Disk drive estimating angular position of spindle motor during spin-up by computing differences in winding current rise times
US7253989B1 (en) 2005-03-21 2007-08-07 Western Digital Technologies, Inc. Disk drive compensation of bias imparted by a flex circuit cable utilizing a dual bias curve estimation scheme
US7265933B1 (en) 2005-06-14 2007-09-04 Western Digital Technologies, Inc. Disk drive computing repeatable run out while actuator arm is pressed against crash stop
US7289288B1 (en) 2006-03-23 2007-10-30 Western Digital Technologies, Inc. Disk drive having hybrid spindle speed control and related method
US7298574B1 (en) 2006-05-10 2007-11-20 Western Digital Technologies, Inc. Servo writing a disk drive using correction values that attenuate phase error propagation
US7304819B1 (en) 2005-06-23 2007-12-04 Western Digital Technologies, Inc. Method for writing repeatable runout correction values to a magnetic disk of a disk drive
US7330019B1 (en) 2006-10-31 2008-02-12 Western Digital Technologies, Inc. Adjusting on-time for a discontinuous switching voltage regulator
US7330327B1 (en) 2004-06-23 2008-02-12 Western Digital Technologies, Inc. Servo writing a disk drive by writing discontinuous spiral tracks to prevent overheating
US7333280B1 (en) 2004-08-03 2008-02-19 Western Digital Technologies, Inc. Servo writing a disk drive by synchronizing a servo write clock to a reference pattern on the disk and compensating for repeatable phase error
US7333290B1 (en) 2006-08-03 2008-02-19 Western Digital Technologies, Inc. Magnetic disk in a disk drive and method having improved null servo burst phasing
US7339761B1 (en) 2006-04-18 2008-03-04 Western Digital Technologies, Inc. Method for wedge time shift calibration in a disk drive
US7365932B1 (en) 2005-12-30 2008-04-29 Western Digital Technologies, Inc. Disk drive comprising an optical sensor for vibration mode compensation
US7388728B1 (en) 2006-09-22 2008-06-17 Western Digital Technologies, Inc. System and method for writing servo sectors in a perpendicular media recording environment
US7391583B1 (en) 2006-07-27 2008-06-24 Western Digital Technologies, Inc. Fault tolerant sync mark detection while servo writing a disk drive from spiral tracks
US7391584B1 (en) 2006-11-07 2008-06-24 Western Digital Technologies, Inc. Compensating for repeatable phase error when servo writing a disk drive from spiral tracks
US7423828B2 (en) * 2006-04-06 2008-09-09 Seagate Technology Llc Off-track write error recovery
US7426086B2 (en) * 2005-08-24 2008-09-16 Hitachi Global Storage Technologies Off track write protection for data storage device
US7433143B1 (en) 2004-09-17 2008-10-07 Western Digital Technologies, Inc. Adjusting track density by changing slope of spiral tracks used to servo write a disk drive
USRE40545E1 (en) * 1999-11-12 2008-10-21 Purchased Patent Management Llc Servo control appartaus and method using absolute value input signals
US7440225B1 (en) 2006-08-21 2008-10-21 Western Digital Technologies, Inc. Disk drive employing pivot friction compensation
US7440210B1 (en) 2004-06-23 2008-10-21 Western Digital Technologies, Inc. Servo writing a disk drive by writing multi-bit sync marks in spiral tracks for improved servo writing
US7450336B1 (en) 2006-10-31 2008-11-11 Western Digital Technologies, Inc. Method for improved repeatable run out learning in a disk drive
US7450334B1 (en) 2007-06-28 2008-11-11 Western Digital Technologies, Inc. Disk drive adjusting predictive caching based on temperature of voice coil motor
US7453661B1 (en) 2006-03-23 2008-11-18 Western Digital Technologies, Inc. Servo writing a disk drive with a controlled overlap near the middle diameter of the disk
US7457071B1 (en) 2006-08-08 2008-11-25 Western Digital Technologies, Inc. Locating an initial servo track in order to servo write a disk drive from spiral tracks
US7466509B1 (en) 2006-09-22 2008-12-16 Western Digital Technologies, Inc. Disk drive operable with first and second servo patterns in a perpendicular media recording environment
US7468855B1 (en) 2007-02-09 2008-12-23 Western Digital Technologies, Inc. Servo writing a disk drive from a number of spiral tracks equal to a non-integer multiple of product servo wedges
US7477471B1 (en) 2007-04-20 2009-01-13 Western Digital Technologies, Inc. Disk drive employing offset compensation for velocity control of a voice coil motor
US7480116B1 (en) 2006-01-20 2009-01-20 Western Digital Technologies, Inc. Disk drive employing coarse position feedback from mechanical position sensor to improve format efficiency
US7489464B1 (en) 2005-02-02 2009-02-10 Western Digital Technologies, Inc. Servo writing a disk drive using a secondary actuator to control skew angle
US7492546B1 (en) 2007-06-13 2009-02-17 Western Digital Technologies, Inc. Providing pre-determined servo position correction values for use during disk drive initialization
US7495857B1 (en) 2005-12-30 2009-02-24 Western Digital Technologies, Inc. Servo writing a disk drive by writing spiral tracks using a mechanical position sensor
US7499236B1 (en) 2004-01-31 2009-03-03 Western Digital Technologies, Inc. Calibrating correlation between PES and off-track displacement by processing high frequency signal in spiral track
US7502197B1 (en) 2007-02-06 2009-03-10 Western Digital Technologies, Inc. Disk drive demodulating a time-based servo pattern
US7502192B1 (en) 2006-07-11 2009-03-10 Western Digital Technologies, Inc. Magnetic disk drive and method for efficiently determining and storing RRO compensation values using a secondary micro-actuator
US7502195B1 (en) 2007-02-09 2009-03-10 Western Digital Technologies, Inc. Compensating for thermal expansion when writing spiral tracks to a disk of a disk drive
US7505223B1 (en) 2007-09-05 2009-03-17 Western Digital Technologies, Inc. Compensating for non-linear thermal expansion when writing spiral tracks to a disk of a disk drive
US7542225B1 (en) 2006-11-17 2009-06-02 Western Digital Technologies, Inc. Disk drive idle mode responsive to flex circuit cable bias changes
US7545593B1 (en) 2004-08-06 2009-06-09 Maxtor Corporation Magnetic storage systems and methods with tighter write fault window to improve reliability
US7548392B1 (en) 2007-05-21 2009-06-16 Western Digital Technologies, Inc. Disk drive controlling a voice coil motor during an emergency unload
US7551390B1 (en) 2007-08-21 2009-06-23 Western Digital Technologies, Inc. Disk drive to characterize misaligned servo wedges
US7558016B1 (en) 2007-04-20 2009-07-07 Western Digital Technologies, Inc. Disk drive servo control techniques for predicting an off-track condition utilizing an estimation filter
US7573670B1 (en) 2007-09-27 2009-08-11 Western Digital Technologies, Inc. Disk drive seeking to OD track and then ramping velocity to implement fast unload
US7576941B1 (en) 2007-10-26 2009-08-18 Western Digital Technologies, Inc. Disk drive writing wedge RRO values in a butterfly pattern
US7580212B1 (en) 2006-03-30 2009-08-25 Western Digital Technologies, Inc. Magnetic disk having efficiently stored WRRO compensation value redundancy information and method for using the redundancy information
US7583470B1 (en) 2007-08-29 2009-09-01 Western Digital Technologies, Inc. Disk drive writing wedge RRO data along a sinusoidal path to compensate for reader/writer offset
US7595954B1 (en) 2006-04-18 2009-09-29 Western Digital Technologies, Inc. Disk drive to estimate repeatable runout (RRO) based upon on an optimal mean square estimation (MSE) learning method
US7602575B1 (en) 2008-05-14 2009-10-13 Western Digital Technologies, Inc. Disk drive adjusting estimated reader/writer offset to achieve target burst crossing signal amplitude when propagating servo sectors
US7616399B1 (en) 2006-12-07 2009-11-10 Western Digital Technologies, Inc. Disk drive servo control techniques to preserve PES continuity
US7619844B1 (en) 2005-12-30 2009-11-17 Western Digital Technologies, Inc. Disk drive comprising a mechanical position sensor to prevent a runaway condition
US7626782B1 (en) 2008-07-23 2009-12-01 Western Digital Technologies, Inc. Disk drive employing iterative learning control for tuning seek servo loop
US7630162B2 (en) 2008-02-04 2009-12-08 Western Digital Technologies, Inc. Disk drive servoing off of first head while determining fly height for second head
US7639447B1 (en) 2008-02-18 2009-12-29 Western Digital Technologies, Inc. Servo track squeeze compensation in a disk drive
US7656607B1 (en) 2008-10-21 2010-02-02 Western Digital Technologies, Inc. Disk drive comprising a servo accelerator employing a dual state variable memory
US7656604B1 (en) 2007-12-10 2010-02-02 Western Digital Technologies, Inc. Disk drive demodulating a spiral track by finding a maximum correlation between a spiral track crossing signal and a time-shifted nominal spiral track crossing signal
US7660067B1 (en) 2007-09-19 2010-02-09 Western Digital Technologies, Inc. Disk drive initializing a coil temperature estimation algorithm using a resistance of the coil estimated during a load operation
US20100035085A1 (en) 2007-02-03 2010-02-11 Wd Media, Inc. Perpendicular magnetic recording medium with improved magnetic anisotropy field
US7663835B1 (en) 2007-06-28 2010-02-16 Western Digital Technologies, Inc. System and method for identifying track squeeze errors (TSEs) of a disk of a disk drive
US7675707B1 (en) 2008-11-21 2010-03-09 Western Digital Technologies, Inc. Disk drive employing repeatable disturbance compensation for fly height control
US7679854B1 (en) 2008-10-29 2010-03-16 Western Digital Technologies, Inc. Head switch operation for a disk drive
US7688538B1 (en) 2007-11-16 2010-03-30 Western Digital Technologies, Inc. Disk drive comprising a disk surface having track addresses of varying width
US7688539B1 (en) 2008-05-14 2010-03-30 Western Digital Technologies, Inc. Disk drive self servo writing spiral tracks by propagating bursts
US7688534B1 (en) 2008-12-11 2010-03-30 Western Digital Technologies, Inc. Extracting repeatable phase error from a spindle motor back EMF signal to generate a servo write clock
US7697233B1 (en) 2008-10-21 2010-04-13 Western Digital Technologies, Inc. Disk drive comprising a servo accelerator implementing state space equations for a plurality of task objects
US7710676B1 (en) 2008-03-27 2010-05-04 Western Digital Technologies, Inc. Disk drive comprising gray code implemented with servo bursts
US7715138B1 (en) 2007-11-20 2010-05-11 Western Digital Technologies, Inc. Disk drive estimating a servo zone after synchronously detecting a servo sync mark
US7729079B1 (en) 2009-01-21 2010-06-01 Western Digital Technologies, Inc. Disk drive estimating fly height using a PLL tuned by a fly height capacitance
US7733189B1 (en) 2007-09-14 2010-06-08 Western Digital Technologies, Inc. Oscillator comprising foldover detection
US7746594B1 (en) 2008-09-29 2010-06-29 Western Digital Technologies, Inc. Disk drive comprising slanted line servo burst sets offset radially
US7746595B1 (en) 2008-09-29 2010-06-29 Western Digital Technologies, Inc. Disk drive comprising slanted line servo bursts having reverse polarity segments
US7746592B1 (en) 2009-02-13 2010-06-29 Western Digital Technologies, Inc. Disk drive detecting defective spiral servo track
US7800856B1 (en) 2009-03-24 2010-09-21 Western Digital Technologies, Inc. Disk drive flushing write cache to a nearest set of reserved tracks during a power failure
US7800857B1 (en) 2009-04-30 2010-09-21 Western Digital Technologies, Inc. Disk drive calibrating voice coil resistance for velocity control of voice coil motor
US7800853B1 (en) 2008-12-03 2010-09-21 Western Digital Technologies, Inc. Correcting servo sectors in a disk drive
US20100265611A1 (en) 2009-04-20 2010-10-21 Samsung Electronics Co., Ltd. Controller, disk drive having the controller, and data processing system having the disk drive
US7839595B1 (en) 2008-01-25 2010-11-23 Western Digital Technologies, Inc. Feed forward compensation for fly height control in a disk drive
US7839600B1 (en) 2009-05-04 2010-11-23 Western Digital Technologies, Inc. Disk drive employing data-based basis function expansion for tuning seek servo loop
US7839591B1 (en) 2008-02-11 2010-11-23 Western Digital Technologies, Inc. Disk drive comprising index spiral track identified by change in sync mark
US7843662B1 (en) 2008-06-10 2010-11-30 Western Digital Technologies, Inc. Servoing on concentric servo sectors of a first disk surface to write a spiral servo track to a second disk surface
US7852588B1 (en) 2008-06-23 2010-12-14 Western Digital Technologies, Inc. Disk drive adjusting gain of shock detector relative to resonant frequency amplitude
US7852592B1 (en) 2008-01-29 2010-12-14 Western Digital Technologies, Inc. Spiral slope approximation of spiral patterns written to a disk of a disk drive
US7864481B1 (en) 2009-01-26 2011-01-04 Western Digital Technologies, Inc. Evaluating distribution of peak signals representing reference track crossings to compensate for thermal expansion when writing spiral tracks to a disk
US7864482B1 (en) 2009-02-27 2011-01-04 Western Digital Technologies, Inc. Disk drive calibrating VCM notch filter by increasing the width and/or the depth of the notch
US7869155B1 (en) 2007-06-08 2011-01-11 Western Digital Technologies, Inc. Ramp detection during servo-writing of a disk for a disk drive
US7876523B1 (en) 2009-08-07 2011-01-25 Western Digital Technologies, Inc. Disk drive initializing position feedforward compensation with velocity feedforward compensation
US7876522B1 (en) 2008-09-30 2011-01-25 Western Digital Technologies, Inc. Disk drive updating estimate of voice coil resistance to account for resistance change prior to unload operation
US7916416B1 (en) 2008-09-29 2011-03-29 Western Digital Technologies, Inc. Disk drive comprising slanted line servo bursts having a varying tilt angle
US7916420B1 (en) 2010-05-14 2011-03-29 Western Digital Technologies, Inc. Disk drive employing comb filter for repeatable fly height compensation
US7916422B1 (en) 2010-05-28 2011-03-29 Western Digital Technologies, Inc. Disk drive rotating phase based servo bursts based on radial location of head
US7916415B1 (en) 2008-03-27 2011-03-29 Western Digital Technologies, Inc. Disk drive decoding binary sequence from phases of servo bursts
US7929238B1 (en) 2008-10-14 2011-04-19 Western Digital Technologies, Inc. Disk drive seeking with a fixed rate clock when crossing servo zones to facilitate zoned servo sectors
US7961422B1 (en) 2009-02-19 2011-06-14 Western Digital Technologies, Inc. Disk drive computing data center off-track from repeatable runout of write servo track and read servo track
US8000053B1 (en) 2008-12-23 2011-08-16 Western Digital Technologies, Inc. Write jog value determination for a disk drive
US8031423B1 (en) 2009-06-26 2011-10-04 Western Digital Technologies, Inc. Disk drive generating actual data TPI profile by combining segments of predetermined data TPI profiles
US8054022B1 (en) 2008-06-26 2011-11-08 Western Digital Technologies, Inc. Reduced acoustic noise during spin-up by driving a spindle motor open loop using sinusoidal signals
US8059357B1 (en) 2010-03-18 2011-11-15 Western Digital Technologies, Inc. Disk drive adjusting fly height when calibrating head/disk contact
US8059360B1 (en) 2010-06-22 2011-11-15 Western Digital Technologies, Inc. Disk drive compensating for radial phase change of repeatable position error due to servo writing from spiral tracks
US8072703B1 (en) 2010-06-23 2011-12-06 Western Digital Technologies, Inc. Disk drive detecting when head is parked on ramp
US8077428B1 (en) 2010-06-23 2011-12-13 Western Digital Technologies, Inc. Disk drive correcting position error signal based on velocity of head
US8078901B1 (en) 2008-06-16 2011-12-13 Western Digital Technologies, Inc. Method for increasing a processor operating frequency when other subsystem demands are low
US8081395B1 (en) 2009-12-15 2011-12-20 Western Digital Technologies, Inc. Continuous digital offset cancellation
US8085020B1 (en) 2008-06-13 2011-12-27 Western Digital Technologies, Inc. Switching voltage regulator employing dynamic voltage scaling with hysteretic comparator
US8116023B1 (en) 2008-12-15 2012-02-14 Western Digital Technologies, Inc. Disk drive comprising preamble aligned zoned servo sectors
US8145934B1 (en) 2009-07-31 2012-03-27 Western Digital Technologies, Inc. Soft start sequencer for starting multiple voltage regulators
US8179626B1 (en) 2009-12-04 2012-05-15 Western Digital Technologies, Inc. Adaptive shock detection
US8189286B1 (en) 2010-05-21 2012-05-29 Western Digital Technologies, Inc. Disk drive employing velocity insensitive servo burst pattern
US20120162806A1 (en) 2010-12-23 2012-06-28 Western Digital Technologies, Inc. Directional write retry for shingled disk drive application
US8213106B1 (en) 2009-03-10 2012-07-03 Western Digital Technologies, Inc. Zoned servo system
US8254222B1 (en) 2011-03-21 2012-08-28 Western Digital Technologies, Inc. Disk drive tuning dual stage actuator servo loop gains from open loop response at target frequency
US8300348B1 (en) 2010-06-25 2012-10-30 Western Digital Technologies, Inc. Disk drive detecting disk boundaries using microactuator
US20120284493A1 (en) 2011-05-03 2012-11-08 Western Digital Technologies, Inc. Booting from a secondary storage device in order to accumulate disk drive performance data
US8315005B1 (en) 2009-11-06 2012-11-20 Western Digital Technologies, Inc. Ramp detection by profile sweep method utilizing integrator values
US8320069B1 (en) 2010-03-18 2012-11-27 Western Digital Technologies, Inc. Disk drive detecting positive correlation in fly height measurements
US20120307400A1 (en) 2011-05-31 2012-12-06 Kabushiki Kaisha Toshiba Disk storage apparatus, disk control apparatus and write control method
US8351174B1 (en) 2009-10-29 2013-01-08 Western Digital Technologies, Inc. Apparatus comprising a brown-out protection circuit for memory devices
US8358114B1 (en) 2009-04-28 2013-01-22 Western Digital Technologies, Inc. Output capacitor current as feedback to control a hysteretic voltage regulator
US8358145B1 (en) 2009-06-19 2013-01-22 Western Digital Technologies, Inc. Self-heating integrated circuit
US8390367B1 (en) 2011-02-15 2013-03-05 Western Digital Technologies, Inc. Ensuring minimum gate speed during startup of gate speed regulator
US8432629B1 (en) 2011-05-23 2013-04-30 Western Digital Technologies, Inc. Disk drive centering sync frames on sync marks of a spiral track
US8432031B1 (en) 2009-12-22 2013-04-30 Western Digital Technologies, Inc. Semiconductor die including a current routing line having non-metallic slots
US20130120870A1 (en) 2011-11-16 2013-05-16 Western Digital Technologies, Inc. Disk drive selecting disturbance signal for feed-forward compensation
US8451697B1 (en) 2011-05-23 2013-05-28 Western Digital Technologies, Inc. Disk drive centering demodulation windows on spiral tracks during a seek operation
US20130148240A1 (en) 2011-12-09 2013-06-13 Western Digital Technologies, Inc. Disk drive charging capacitor using motor supply voltage during power failure
US8482873B1 (en) 2008-02-18 2013-07-09 Western Digital Technologies, Inc. Disk drive employing pulse width modulation of head control signal
US8498076B1 (en) 2010-04-22 2013-07-30 Western Digital Technologies, Inc. Disk drive biasing timing recovery measurements for spiral tracks based on radial location of head
US8498172B1 (en) 2010-08-31 2013-07-30 Western Digital Technologies, Inc. Data storage device evaluating frequency range of supply voltage to detect power failure
US8508881B1 (en) 2011-05-26 2013-08-13 Western Digital Technologies, Inc. Disk drive employing system inversion for tuning seek to settle servo loop
US8531798B1 (en) 2010-12-13 2013-09-10 Western Digital Technologies, Inc. Disk drive adjusting servo burst signals to compensate for radial velocity of the head
US8537486B2 (en) 2011-08-10 2013-09-17 Western Digital Technologies, Inc. Disk drive writing spiral tracks on a slave surface using repeatable runout compensation for a master surface
US8542455B2 (en) 2011-11-16 2013-09-24 Western Digital Technologies, Inc. Disk drive upsampling servo control signal
US8553351B1 (en) 2011-10-06 2013-10-08 Western Digital Technologies, Inc. Disk drive correcting track ID in response to an estimated radial location and a burst PES
US8564899B2 (en) 2011-08-09 2013-10-22 Western Digital Technologies, Inc. Disk drive decreasing a settle delay based on speed that a settle parameter adapts
US8576506B1 (en) 2012-06-21 2013-11-05 Western Digital Technologies, Inc. Disk drive estimating reader/writer gap across servo zones
US8605384B1 (en) 2012-11-06 2013-12-10 Western Digital Technologies, Inc. Disk drive performing lifetime logging of microactuator sensitivity
US8605382B1 (en) 2011-06-08 2013-12-10 Western Digital Technologies, Inc. Disk drive to load a head to a load/unload (LUL) zone of a disk
US8610391B1 (en) 2011-06-29 2013-12-17 Western Digital Technologies, Inc. Disk drive optimizing spindle motor torque by adjusting leading phase angle during spin-up
US8611040B1 (en) 2012-09-27 2013-12-17 Western Digital Technologies, Inc. Disk drive adjusting microactuator gain by injecting a sinusoid into a servo control system
US8619385B1 (en) 2011-01-28 2013-12-31 Western Digital Technologies, Inc. Disk drive biasing sync pattern of an extended sync mark
US8625215B1 (en) * 2011-03-21 2014-01-07 Marvell International Ltd. Method and system for compensating for adjacent tracks during writing of data
US8630059B1 (en) 2012-02-29 2014-01-14 Western Digital Technologies, Inc. Methods for closed-loop compensation of ultra-high frequency disturbances in hard disk drives and hard disk drives utilizing same
US8630054B2 (en) 2011-09-21 2014-01-14 Western Digital Technologies, Inc. Systems and methods for data throttling during disk drive power down
US8634283B1 (en) 2011-08-08 2014-01-21 Western Digital Technologies, Inc. Disk drive performing in-drive spiral track writing
US8634154B1 (en) 2011-08-08 2014-01-21 Western Digital Technologies, Inc. Disk drive writing a sync mark seam in a bootstrap spiral track
US8643976B1 (en) 2007-01-31 2014-02-04 Western Digital Technologies, Inc. Method for improved repeatable runout learning in a disk drive
US8649121B1 (en) 2012-03-28 2014-02-11 Western Digital Technologies, Inc. Disk drive tuning speed control loop for a spindle motor
US8654467B1 (en) 2012-04-16 2014-02-18 Western Digital Technologies, Inc. Disk drive increasing bandwidth of cutoff filter while reading servo sector preamble
US8654466B1 (en) 2011-11-21 2014-02-18 Western Digital Technologies, Inc. Calculation of head media separation (HMS) from servo preamble in a hard disk drive
US8665546B1 (en) 2010-01-07 2014-03-04 Western Digital Technologies, Inc. Adaptive threshold for detecting touchdown or contamination
US8665551B1 (en) 2011-12-22 2014-03-04 Western Digital Technologies, Inc. Disk drive adjusting gain and offset of BEMF velocity sensor during self writing of spiral tracks
US8670206B1 (en) 2012-03-27 2014-03-11 Western Digital Technologies, Inc. Disk drive estimating repeatable runout of reference pattern based on repeatable runout of phase error
US8687312B1 (en) 2010-11-30 2014-04-01 Western Digital Technologies, Inc. Edge detection for disk drives
US8693123B1 (en) 2011-06-27 2014-04-08 Western Digital Technologies, Inc. Disk drive correcting high order gray code using track estimator and decoding low order track code separately
US8693134B1 (en) 2011-06-23 2014-04-08 Western Digital Technologies, Inc. Alternating wedge repeatable runout (WRRO) pattern
US8699173B1 (en) 2011-09-01 2014-04-15 Western Digital Technologies, Inc. Disk drive detecting touchdown event by evaluating frequency response of a touchdown metric
US8711027B1 (en) 2012-11-19 2014-04-29 Western Digital Technologies, Inc. Analog-to-digital converter with input voltage biasing DC level of resonant oscillator
US8717699B1 (en) 2012-01-10 2014-05-06 Western Digital Technologies, Inc. Voltage quadrupler comprising a second charging capacitor charged using a first charging capacitor
US8717704B1 (en) 2012-02-28 2014-05-06 Western Digital Technologies, Inc. Disk drive defining non-circular data tracks relative to a rotation axis of the disk
US8717696B1 (en) 2012-12-04 2014-05-06 Western Digital Technologies, Inc. Disk drive adjusting noise spectrum to reduce resonance excitation of shock detector
US8724253B1 (en) 2012-03-27 2014-05-13 Western Digital Technologies, Inc. Disk drive adjusting demodulation window for spiral track using timing feed-forward compensation
US8724245B1 (en) 2012-06-21 2014-05-13 Western Digital Technologies, Inc. Disk drive employing overlapping servo zones to facilitate servo zone crossing
US8724524B2 (en) 2005-06-10 2014-05-13 Panasonic Corporation Wireless communication apparatus and wireless communication method
US8737008B1 (en) 2011-05-12 2014-05-27 Western Digital Technologies, Inc. Disk drive adjusting gain of spindle motor compensator based on a ratio of spin speeds
US8743504B1 (en) 2012-07-25 2014-06-03 Western Digital Technologies, Inc. Servoing on zoned concentric servo sectors of a first disk surface to write a spiral servo track to a second disk surface
US8743503B1 (en) 2013-03-11 2014-06-03 Western Digital Technologies, Inc. Disk drive updating compensation values for multiple servo sectors based on PES generated for current servo sector
US8743495B1 (en) 2011-06-03 2014-06-03 Western Digital Technologies, Inc. Disk drive detecting track squeeze when circular tracks are defined from non-circular servo tracks
US8749904B1 (en) 2012-02-28 2014-06-10 Western Digital Technologies, Inc. Disk drive compensating for track squeeze by writing non-circular servo tracks
US8760796B1 (en) 2011-06-03 2014-06-24 Western Digital Technologies, Inc. Reducing acoustic noise in a disk drive when exiting idle mode
US8767332B1 (en) 2013-04-03 2014-07-01 Western Digital Technologies, Inc. Disk drive predicting off-track error due to disturbances occurring over different frequency ranges
US8767354B1 (en) 2011-12-08 2014-07-01 Western Digital Technologies, Inc. Data storage device employing cascaded voltage regulators during power failure
US8767343B1 (en) 2012-04-24 2014-07-01 Western Digital Technologies, Inc. Disk drive increasing integrator output range to complete seek operation
US8773787B1 (en) 2012-03-29 2014-07-08 Western Digital Technologies, Inc. Changing the performance level of a disk drive
US8780479B1 (en) 2013-05-17 2014-07-15 Western Digital Technologies, Inc. Disk drive executing jerk seeks to rotate pivot ball bearings relative to races
US8780489B1 (en) 2012-11-20 2014-07-15 Western Digital Technologies, Inc. Disk drive estimating microactuator gain by injecting a sinusoid into a closed loop servo system
US8780477B1 (en) 2012-06-21 2014-07-15 Western Digital Technologies, Inc. Disk drive adjusting servo timing to compensate for transient when crossing a servo zone boundary
US8792202B1 (en) 2013-08-29 2014-07-29 Western Digital Technologies, Inc. Disk drive adjusting rotation speed of disk to compensate for blind area when measuring frequency response of servo control system
US8797664B1 (en) 2012-12-22 2014-08-05 Western Digital Technologies, Inc. Polarity detection of piezoelectric actuator in disk drive
US8804267B2 (en) 2012-11-07 2014-08-12 Western Digital Technologies, Inc. Disk drive predicting spindle motor failure by evaluating current draw relative to temperature
US8824262B1 (en) 2013-08-19 2014-09-02 Western Digital Technologies, Inc. Disk drive accounting for sinusoidal offset between heads when executing a rotational position optimization algorithm
US8824081B1 (en) 2012-03-13 2014-09-02 Western Digital Technologies, Inc. Disk drive employing radially coherent reference pattern for servo burst demodulation and fly height measurement

Patent Citations (353)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6181502B2 (en)
US6181493B2 (en)
US6347018B1 (en) 1990-09-18 2002-02-12 Rodime Plc Digital servo control system for use in disk drives
US6111714A (en) * 1997-03-27 2000-08-29 International Business Machines Corporation Disk drive and write control method for a disk drive
US6014283A (en) 1997-05-15 2000-01-11 Western Digital Corporation Non-quadrature servo burst pattern for micro-jogging a magnetoresistive head in a magnetic disk drive
US6052250A (en) 1997-08-25 2000-04-18 Western Digital Corporation Disk drive with separately determined servo and data track pitch
US6141175A (en) 1997-10-08 2000-10-31 Western Digital Corporation Repeatable runout cancellation in sectored servo disk drive positioning system
US6310742B1 (en) 1997-10-08 2001-10-30 Western Digital Technologies, Inc. Repeatable runout cancellation in sectored servo disk drive positioning system
US6078453A (en) 1997-11-12 2000-06-20 Western Digital Corporation Method and apparatus for optimizing the servo read channel of a hard disk drive
US6067206A (en) 1997-11-18 2000-05-23 Western Digital Corporation Method and apparatus to compensate for servo wedge rotational offset after a head switch
US6122135A (en) 1997-12-19 2000-09-19 Western Digital Corporation Disk drive with voice coil motor rise time manager
US6243223B1 (en) 1998-01-15 2001-06-05 Western Digital Corporation Disk drive with servo burst phasing for improved linearity and off-track performance with a wide reading transducer
US6292320B1 (en) 1998-03-23 2001-09-18 Western Digital Technologies, Inc. Disk drive with dual stage actuator radial offset calibration
US6101065A (en) 1998-03-30 2000-08-08 Western Digital Corporation Disk drive with seek profile selection based on read/write operation
US6198584B1 (en) 1998-04-30 2001-03-06 Western Digital Corporation Disk drive with staggered calibration bursts that are disposably located in data regions and method of using the same for calibrating a read head
US6091564A (en) 1998-04-30 2000-07-18 Western Digital Corporation Disk drive with calibration bursts that are recorded on a spiral and method of recording the same
US6181493B1 (en) 1998-06-05 2001-01-30 Seagate Technology Llc Write fault thresholds adaptive by head and disc location in a disc drive
US6122133A (en) 1998-06-17 2000-09-19 Western Digital Corporation Hybrid method of determining a fractional track position of a read transducer in a hard disk drive
US6160368A (en) 1998-06-22 2000-12-12 Western Digital Corporation Faster spin-down operation in a disk drive by utilizing pulsed braking
US6342984B1 (en) 1998-07-01 2002-01-29 Western Digital Technologies, Inc Disk drive including DC to DC voltage converter for increasing voltage to its spindle motor and VCM
US6181502B1 (en) 1998-07-01 2001-01-30 Western Digital Corporation Faster access time in a disk drive by utilizing increased VCM potential voltage
US6198590B1 (en) 1998-07-21 2001-03-06 Western Digital Corporation Disk drive employing method of spinning down its spindle motor to reduce the time required for subsequently spinning it up
US6204988B1 (en) 1998-08-24 2001-03-20 Western Digital Corporation Disk drive capable of autonomously evaluating and adapting the frequency response of its servo control system
US6215608B1 (en) 1998-08-31 2001-04-10 International Business Machines Corporation Hardware inhibit for a disk drive digital servo control system
US6052076A (en) 1998-10-14 2000-04-18 Western Digital Corporation Digital-to-analog converter having high resolution and high bandwidth
US6195222B1 (en) 1998-11-04 2001-02-27 Western Digital Corporation Disk drive with seek profile selection based on a queued vs. non-queued environment
US6094020A (en) 1998-11-18 2000-07-25 Western Digital Corporation Disk drive utilizing Bemf of spindle motor to increase VCM voltage during seeks
US6320718B1 (en) 1999-01-07 2001-11-20 Western Digital Technologies, Inc. Disk drive with zero read offset in reserved area and method of making same
US6369974B1 (en) 1999-02-09 2002-04-09 Western Digital Technologies, Inc. Disk drive with method of constructing a continuous position signal and constrained method of linearizing such position signal while maintaining continuity
US6421197B1 (en) 1999-02-22 2002-07-16 Seagate Technology Llc Optimal reader/writer offsets and write fault thresholds in a disc drive
US6104153A (en) 1999-02-23 2000-08-15 Western Digital Corporation Disk drive employing method of spinning down its spindle motor to reduce the time required for spinning it down and subsequently spinning it up
US6285521B1 (en) 1999-03-25 2001-09-04 Western Digital Technologies, Inc. Disk drive employing power source modulation for reducing power consumption
US6369972B1 (en) 1999-05-14 2002-04-09 Western Digital Technologies, Inc. Temperature monitoring method of a disk drive voice coil motor from a traveled distance
US6507450B1 (en) 1999-06-11 2003-01-14 Western Digital Technologies, Inc. Method of continuously recording servo bursts along one continuous, single helix spiral
US6498698B1 (en) 1999-06-29 2002-12-24 Western Digital Technologies, Inc. Servowriter employing method of unlatching actuator arm using VCM voltage limiting circuit to limit actuator arm velocity
US6496324B1 (en) 1999-06-29 2002-12-17 Western Digital Technologies, Inc. Disk drive employing method of unlatching actuator arm using VCM voltage limiting circuit to limit actuator arm velocity
USRE40545E1 (en) * 1999-11-12 2008-10-21 Purchased Patent Management Llc Servo control appartaus and method using absolute value input signals
US6496320B1 (en) 2000-02-09 2002-12-17 Seagate Technology Llc Adaptive attenuation of multi-axis vibrational disturbance
US6476996B1 (en) 2000-02-15 2002-11-05 Western Digital Technologies, Inc. Disk drive comprising an actuator driver circuit for retracting a head independent of a servo microprocessor when a spindle speed fault mode is detected
US6281652B1 (en) 2000-03-24 2001-08-28 Western Digital Corporation Method of using two low-resolution DACS for converting high-resolution digital demands into analog output signals that monotonically drive an actuator motor in a disk drive
US6614618B1 (en) 2000-03-31 2003-09-02 Western Digital Technologies, Inc. Disk drive with feed-forward control path that receives a reference position signal to apply a feed-forward command effort at a rate greater than a servo sampling rate
US6614615B1 (en) 2000-03-31 2003-09-02 Western Digital Technologies, Inc. Disk drive with adaptive control path that produces an adaptive control effort based on a characterized deviation between actual and modeled plant response
US6574062B1 (en) 2000-04-19 2003-06-03 Western Digital Technologies, Inc. Disk drive comprising a demand limit circuit for enhancing power management during spin down
US6493169B1 (en) 2000-04-19 2002-12-10 Western Digital Technologies, Inc. Disk drive employing spindle motor commutation time variation for reducing acoustic noise
US6549359B1 (en) 2000-04-19 2003-04-15 Western Digital Technologies, Inc. Disk drive comprising spin down circuitry having a current limit circuit for enhancing power and braking control
US6549361B1 (en) 2000-04-19 2003-04-15 Western Digital Technologies, Inc. Disk drive comprising spin down circuitry having a power clamp circuit for enhancing power and braking control
US6577465B1 (en) 2000-04-19 2003-06-10 Western Digital Technologies, Inc. Disk drive comprising spin down circuitry having a programmable signal generator for enhancing power and braking control
US6534936B2 (en) 2000-04-28 2003-03-18 Western Digital Technologies, Inc. Disk drive employing method of spinning up spindle motor including detecting BEMF polarity change for selecting initial commutation state
US6717757B1 (en) 2000-05-25 2004-04-06 Maxtor Corporation Variable write fault protection window
US6636377B1 (en) 2000-06-30 2003-10-21 Western Digital Technologies, Inc. Method of tuning feed-forward control in a disk drive
US6882489B1 (en) * 2000-08-15 2005-04-19 Maxtor Corporation Dynamic off-track detector
US6545835B1 (en) 2000-08-31 2003-04-08 Western Digital Technologies, Inc. Method and apparatus for RRO learning before and after shipping to cancel RRO in a disk drive
US6707635B1 (en) 2000-10-05 2004-03-16 Western Digital Technologies, Inc. Method and apparatus for RRO learning on alternate tracks before and after shipping to cancel RRO in a disk drive
US6690536B1 (en) 2000-10-31 2004-02-10 Western Digital Technologies, Inc. Disk drive employing VCM demand current to calibrate VCM IR voltage for velocity control of an actuator arm
US6867944B1 (en) 2000-10-31 2005-03-15 Western Digital Technologies, Inc. Disk drive comprising VCM stall detector for velocity control of an actuator arm
US6795268B1 (en) 2000-10-31 2004-09-21 Western Digital Technologies, Inc. Disk drive employing seek time vcm ir voltage calibration for velocity control of an actuator arm
US6940679B1 (en) 2000-11-07 2005-09-06 Maxtor Corporation Method and apparatus for increasing track density by adapting write fault gate to position error signal as it varies from ID to OD
US6760186B1 (en) 2000-11-30 2004-07-06 Western Digital Technologies, Inc. Disk drive having first-written servo wedge marked and method for forming marked servo wedges
US6731450B1 (en) 2000-11-30 2004-05-04 Western Digital Technologies, Inc. Disk drive control system and method for determining the temperature of an actuator coil
US6462896B1 (en) 2000-11-30 2002-10-08 Western Digital Technologies, Inc. Method for minimizing adjacent track data loss during a write operation in a disk drive
US6724564B1 (en) 2000-11-30 2004-04-20 Western Digital Technologies, Inc. Seek distance dependent variable max VCM seek current to control thermal rise in VCM's
US6914743B1 (en) 2000-11-30 2005-07-05 Western Digital Technologies, Inc. Vibration cancellation in a disk drive by using an acceleration sensor and adaptively adjusting its gain to minimize external acceleration effects
US6693764B1 (en) 2001-01-31 2004-02-17 Western Digital Technologies, Inc. Method and disk drive for improving head position accuracy during track following through real-time identification of external vibration
US6538839B1 (en) 2001-01-31 2003-03-25 Western Digital Technologies, Inc. Disk drive employing adaptive feed-forward vibration compensation to enhance a retry operation
US6560056B1 (en) 2001-01-31 2003-05-06 Western Digital Technologies, Inc. Disk drive comprising a motor driver IC employing a serial interface for initiating the transmission of real-time status data to a controller IC
US6975468B1 (en) * 2001-02-16 2005-12-13 Maxtor Corporation Method to accurately predict hard error rates resulting from encroachment
US6791785B1 (en) 2001-02-28 2004-09-14 Western Digital Technologies, Inc. Disk drive with efficient coil temperature estimation
US6710953B1 (en) 2001-03-30 2004-03-23 Western Digital Technologies, Inc. Method and disk drive for improving data storage capacity of data tracks using push-down wedges
US6781780B1 (en) * 2001-06-21 2004-08-24 Western Digital Technologies, Inc. Method and system for preventing data loss from an off-track write condition in a disk drive by rewriting data buffered from an adjacent track
US7035026B2 (en) 2001-07-31 2006-04-25 Western Digital Technologies, Inc. Method of manufacturing and disk drive produced by measuring the read and write widths and varying the track pitch in the servo-writer
US6885514B1 (en) 2001-07-31 2005-04-26 Western Digital Technologies, Inc. Method of manufacturing and disk drive produced by measuring the read and write widths and varying the track pitch in the servo-writer
US6747837B1 (en) 2001-08-31 2004-06-08 Western Digital Technologies, Inc. Disk drive comprising an integrator for controlling a VCM actuator and transformer for controlling a piezoelectric actuator
US6788483B1 (en) 2001-08-31 2004-09-07 Western Digital Technologies, Inc. Disk drive comprising a programmable inverting voltage regulator configured relative to the disk drive's mode of operation
US6714371B1 (en) 2001-08-31 2004-03-30 Western Digital Technologies, Inc. Method and disk drive for shock estimation and write termination control
US6738220B1 (en) 2001-09-28 2004-05-18 Western Digital Technologies, Inc. Servo settling by utilization of a bias torque offset value which depends on the memory of previous seek operations
US6714372B1 (en) 2001-09-28 2004-03-30 Western Digital Technologies, Inc. Method of manufacturing a disk drive by measuring the read width in the servo-writer to set the write unsafe limit
US6710966B1 (en) 2001-10-23 2004-03-23 Western Digital Technologies, Inc. Method for reducing an effect of vibration on a disk drive during a track following operation by adjusting an adaptive-filter gain applied to an acceleration sensor signal
US6568268B1 (en) 2001-10-31 2003-05-27 Western Digital Technologies, Inc. Multi-axis accelerometer comprising a mass suspended by springs above an optical sensor
US6484577B1 (en) 2001-10-31 2002-11-26 Western Digital Technologies, Inc. Accelerometer signal processor comprising variable oscillators and counters
US6735033B1 (en) 2001-12-10 2004-05-11 Western Digital Technologies, Inc. Method for recovering from shock events occurring to a disk drive during data write operations to improve data reliability
US6977789B1 (en) 2002-01-31 2005-12-20 Western Digital Technologies, Inc. Disk drive for circular self servo writing and spiral self servo writing using prewritten reference servo bursts
US6920004B1 (en) 2002-03-29 2005-07-19 Western Digital Technologies, Inc. Method for adjusting a delay time for opening a servo sector detection window in a disk drive having a spiral track
US6992848B1 (en) 2002-03-29 2006-01-31 Western Digital Technologies, Inc. Using an external spiral servo writer to write spiral reference patterns to a disk to facilitate writing product servo bursts to the disk
US6735041B1 (en) 2002-03-29 2004-05-11 Western Digital Technologies, Inc. Method for seeking in a magnetic disk drive having a spiral track
US6975480B1 (en) 2002-04-17 2005-12-13 Western Digital Technologies, Inc. Method for determining repeatable runout cancellation values in a magnetic disk drive using filtering
US7184230B1 (en) 2002-06-01 2007-02-27 Western Digital Technologies, Inc. System and method for processing track identifier errors to mitigate head instability in data storage devices
US6795262B1 (en) 2002-06-28 2004-09-21 Western Digital Technologies, Inc. Method of modifying on-track declaration algorithm of a disk drive based upon detection of external vibration condition
US6847502B1 (en) 2002-06-28 2005-01-25 Western Digital Technologies, Inc. Repeatable runout determination within a rotating media storage device
US6967458B1 (en) 2002-07-31 2005-11-22 Western Digital Technologies, Inc. Decreasing spin up time in a disk drive by adjusting a duty cycle of a spindle motor PWM signal to maintain constant average input current
US7006320B1 (en) 2002-07-31 2006-02-28 Western Digital Technologies, Inc. Disk drive comprising a multi-phase spindle motor having a center tap connectable to a secondary supply voltage
US6876508B1 (en) 2002-07-31 2005-04-05 Western Digital Technologies, Inc. Disk drive comprising control circuitry powered by a secondary voltage supplied by a center tap of a spindle motor during a normal operating mode
US7046472B1 (en) 2002-08-30 2006-05-16 Western Digital Technologies, Inc. Method and apparatus for self servowriting of tracks of a disk drive using an observer based on an equivalent one-dimensional state model
US6924961B1 (en) 2002-08-30 2005-08-02 Western Digital Technologies, Inc. Method and apparatus for self servowriting of tracks of a disk drive using an observer based on an equivalent one-dimensional state model
US6826007B1 (en) 2002-08-30 2004-11-30 Western Digital Technologies, Inc. Disk drive using dual slope integrator to extract velocity of an actuator arm from a back EMF voltage
US6826006B1 (en) 2002-09-30 2004-11-30 Western Digital Technologies, Inc. Method for recursively determining repeatable runout cancellation values in a magnetic disk drive
US6819518B1 (en) 2002-10-24 2004-11-16 Western Digital Technologies, Inc. Method and apparatus for self servowriting of tracks of a disk drive using a servo control loop having a two-dimensional digital state compensator
US6934114B1 (en) 2002-10-24 2005-08-23 Western Digital Technologies, Inc. Reduced bit number wedge identification techniques within a rotating media storage device
US6952322B1 (en) 2002-11-27 2005-10-04 Western Digital Technologies, Inc. Disk drive reading servo sectors recorded at a relative offset on multiple disk surfaces to increase the servo sample rate
US20040109253A1 (en) 2002-12-09 2004-06-10 Hitachi Global Storage Technologies Japan, Ltd. Magnetic recording disk drive and method for ensuring magnetic recording function thereof
US7050258B1 (en) 2002-12-24 2006-05-23 Western Digital Technologies, Inc. Disk drive and method for improved disk rotation control
US7113365B1 (en) 2002-12-24 2006-09-26 Western Digital Technologies, Inc. Disk drive comprising a spindle motor having a windings shield for reduced disk voltage coupling
US7050249B1 (en) 2002-12-24 2006-05-23 Western Digital Technologies, Inc. System and method for processing track identification data in a disk drive
US6972922B1 (en) 2003-02-07 2005-12-06 Western Digital Technologies, Inc. Disk drive having internal data structures for efficiently storing repeatable runout cancellation information
US7126781B1 (en) 2003-02-28 2006-10-24 Western Digital Technologies, Inc. Disk drive employing a multi-stage pulse width modulated voice coil motor driver
US6850383B1 (en) 2003-02-28 2005-02-01 Western Digital Technologies, Inc. Disk drive comprising current sense circuitry for a voice coil motor
US7027256B1 (en) 2003-02-28 2006-04-11 Western Digital Technologies, Inc. Disk drive having servo sectors that store repeatable runout correction values and related error correction code data
US6934135B1 (en) 2003-02-28 2005-08-23 Western Digital Technologies, Inc. Disk drive monitoring a supply current to protect motor driver circuits
US6850384B1 (en) 2003-02-28 2005-02-01 Western Digital Technologies, Inc. Disk drive comprising oscillators and counters for sensing current in a voice coil motor
US6900959B1 (en) 2003-03-31 2005-05-31 Western Digital Technologies, Inc. Disk drive comprising an offset-nulling amplifier for detecting a back EMF voltage of a voice coil motor
US6972539B1 (en) 2003-04-30 2005-12-06 Western Digital Technologies, Inc. Disk drive employing commutation phase modulation and current modulation of a spindle motor
US6970319B1 (en) 2003-05-27 2005-11-29 Western Digital Technologies, Inc. Disk drive comprising a pulse width modulated demand limit circuit for enhancing power management during spin-down
US6882496B1 (en) 2003-05-30 2005-04-19 Western Digital Technologies, Inc. Method for adaptively allocating data storage tracks in a disk drive to improve seek performance
US6903897B1 (en) 2003-06-27 2005-06-07 Western Digital Technologies, Inc. Performance of a rotary actuator in a disk drive
US6968422B1 (en) 2003-06-27 2005-11-22 Western Digital Technologies, Inc. Disk drive employing a modified rotational position optimization algorithm to account for external vibrations
US6965488B1 (en) 2003-06-27 2005-11-15 Western Digital Technologies, Inc. Disk drive controlling ripple current of a voice coil motor when driven by a PWM driver
US6924960B1 (en) 2003-07-31 2005-08-02 Western Digital Technologies, Inc. Timing compensation in a self-servowriting system
US7209321B1 (en) 2003-07-31 2007-04-24 Western Digital Technologies, Inc. Disk drive pulse width modulating a voice coil motor using model reference current feedback
US6900958B1 (en) 2003-07-31 2005-05-31 Western Digital Technologies, Inc. Method and disk drive for improving head position accuracy during track following through real-time identification of external vibration and monitoring of write-unsafe occurrences
US6924959B1 (en) 2003-08-29 2005-08-02 Western Digital Technologies, Inc. Reducing estimation period for repeatable runout errors in a disk drive
US7097110B2 (en) 2003-09-02 2006-08-29 Texas Instruments Incorporated Temperature compensation systems and methods for use with read/write heads in magnetic storage devices
US7116505B1 (en) 2003-09-30 2006-10-03 Western Digital Technologies, Inc. Reducing the length of servo-wedges in a disk drive
US6987639B1 (en) 2003-09-30 2006-01-17 Western Digital Technologies, Inc. Disk drive modifying a rotational position optimization algorithm based on motor capability of a VCM
US6999263B1 (en) 2003-10-24 2006-02-14 Western Digital Technologies, Inc. Method and apparatus for self servowriting of tracks of a disk drive using a servo control loop having a two-dimensional weighted digital state compensator
US7064918B1 (en) 2003-10-31 2006-06-20 Western Digital Technologies, Inc. Reducing head gain calibration time in a disk drive
US6914740B1 (en) 2003-11-26 2005-07-05 Western Digital Technologies, Inc. Disk drive employing BEMF spindle speed control or wedge spindle speed control
US6958881B1 (en) 2003-11-26 2005-10-25 Western Digital Technologies, Inc. Disk drive control system having a servo processing accelerator circuit
US6954324B1 (en) 2003-11-26 2005-10-11 Western Digital Technologies, Inc. Disk drive disabling BEMF detection window to reduce acoustic noise while using wedge spindle speed control
US7061714B1 (en) 2003-12-19 2006-06-13 Western Digital Technologies, Inc. Disk drive modifying estimated seek times for a rotational position optimization algorithm based on change in estimated seek time parameter
US6989954B1 (en) 2004-01-31 2006-01-24 Western Digital Technologies, Inc. Demodulating servo sectors and spiral tracks using common circuitry
US7499236B1 (en) 2004-01-31 2009-03-03 Western Digital Technologies, Inc. Calibrating correlation between PES and off-track displacement by processing high frequency signal in spiral track
US7224546B1 (en) 2004-01-31 2007-05-29 Western Digital Technologies, Inc. Disk drive employing a calibrated brake pulse to reduce acoustic noise when latching an actuator arm
US7113362B1 (en) 2004-01-31 2006-09-26 Western Digital Technologies, Inc. Servo writing a disk drive by processing spiral tracks in an interleaved manner
US7016134B1 (en) 2004-01-31 2006-03-21 Western Digital Technologies, Inc. Using an external spiral servo writer to write spiral tracks to a disk to facilitate writing product servo sectors to the disk
US7212364B1 (en) 2004-01-31 2007-05-01 Western Digital Technologies, Inc. Servo writing a disk drive by synchronizing a servo write clock in response to a sync mark reliability metric
US6937423B1 (en) 2004-02-06 2005-08-30 Western Digital Technologies, Inc. Reducing effects of rotational vibration in disk drive
US6980389B1 (en) 2004-02-27 2005-12-27 Western Digital Technologies, Inc. Disk drive having a disk including a servo burst pattern having a normal servo burst field and a quadrature servo burst field
US7027257B1 (en) 2004-04-01 2006-04-11 Western Digital Technologies, Inc. Disk drive having a disk including a servo burst pattern in which a phase difference between radially adjacent servo bursts is less than 180 degrees
US6999267B1 (en) 2004-04-28 2006-02-14 Western Digital Technologies, Inc. Method for iteratively determining repeatable runout cancellation values in a magnetic disk drive
US7180703B1 (en) 2004-05-15 2007-02-20 Western Digital Technologies, Inc. Disk drive comprising a spindle motor employing anionic/cationic lubricant to reduce disk surface potential
US7023640B1 (en) 2004-05-27 2006-04-04 Western Digital Technologies, Inc. Acceleration disturbance detection subsystem for use with disk drives
US7253582B1 (en) 2004-05-28 2007-08-07 Western Digital Technologies, Inc. Disk drive estimating angular position of spindle motor during spin-up by computing differences in winding current rise times
US6937420B1 (en) 2004-05-28 2005-08-30 Western Digital Technologies, Inc. Determining repeatable runout cancellation information using PES information generated during self servo-writing operations
US7054098B1 (en) 2004-06-01 2006-05-30 Western Digital Technologies, Inc. Disk drive employing asymmetric acceleration/deceleration pulses for acoustic noise reduction during unlatch
US7023637B1 (en) 2004-06-01 2006-04-04 Western Digital Technologies, Inc. Disk drive having a disk including a servo burst pattern that improves the signal to noise ratio during track following for writing
US7068463B1 (en) 2004-06-14 2006-06-27 Western Digital Technologies, Inc. Disk drive employing a velocity profile and back EMF feedback to control a voice coil motor
US7440210B1 (en) 2004-06-23 2008-10-21 Western Digital Technologies, Inc. Servo writing a disk drive by writing multi-bit sync marks in spiral tracks for improved servo writing
US7330327B1 (en) 2004-06-23 2008-02-12 Western Digital Technologies, Inc. Servo writing a disk drive by writing discontinuous spiral tracks to prevent overheating
US6963465B1 (en) 2004-06-29 2005-11-08 Western Digital Technologies, Inc. Method for preventing radial error propagation during self-servowriting of tracks in a magnetic disk drive
US6992851B1 (en) 2004-06-30 2006-01-31 Western Digital Technologies, Inc. Method for nonsequentially writing reference spiral servo patterns to a disk to compensate for disk expansion
US6967811B1 (en) 2004-07-02 2005-11-22 Western Digital Technologies, Inc. Disk drive having first and second seek operating modes for controlling voice coil motor temperature rise
US7110208B1 (en) 2004-07-30 2006-09-19 Western Digital Technologies, Inc. Method for improving servo performance in a disk drive having tracks with mini servo wedges
US7248426B1 (en) 2004-07-30 2007-07-24 Western Digital Technologies, Inc. Servo writing a disk drive from spiral tracks by shifting a demodulation window an integer number of sync mark intervals
US7301717B1 (en) 2004-07-30 2007-11-27 Western Digital Technologies, Inc. Servo writing a disk drive by integrating a spiral track read signal
US7333280B1 (en) 2004-08-03 2008-02-19 Western Digital Technologies, Inc. Servo writing a disk drive by synchronizing a servo write clock to a reference pattern on the disk and compensating for repeatable phase error
US7545593B1 (en) 2004-08-06 2009-06-09 Maxtor Corporation Magnetic storage systems and methods with tighter write fault window to improve reliability
US7433143B1 (en) 2004-09-17 2008-10-07 Western Digital Technologies, Inc. Adjusting track density by changing slope of spiral tracks used to servo write a disk drive
US6987636B1 (en) 2004-09-17 2006-01-17 Western Digital Technologies, Inc. Adjusting track density over disk radius by changing slope of spiral tracks used to servo write a disk drive
US7068459B1 (en) 2004-09-20 2006-06-27 Western Digital Technologies, Inc. Adjusting track density by changing PES algorithm when servo writing a disk drive from spiral tracks
US6992852B1 (en) 2004-10-15 2006-01-31 Western Digital Technologies, Inc. Method for reducing disk thermal expansion effects while writing reference spiral servo patterns to a disk of a disk drive
US7068451B1 (en) 2004-11-16 2006-06-27 Western Digital Technologies, Inc. Disk drive estimating a sinusoidal error in a wedge time period due to eccentricity in disk rotation
US6972540B1 (en) 2004-11-19 2005-12-06 Western Digital Technologies, Inc. Disk drive employing wedge spindle speed control with eccentricity compensation
US7251098B1 (en) 2004-11-19 2007-07-31 Western Digital Technologies, Inc. Disk drive adjusting write clock frequency to compensate for eccentricity in disk rotation
US7068461B1 (en) 2004-11-29 2006-06-27 Western Digital Technologies, Inc. Servo writing a disk drive by overwriting a harmonic frequency fill pattern in the servo burst area
US7209305B2 (en) 2005-01-06 2007-04-24 Hitachi Global Storage Technologies Netherlands, B.V. Method for determining unique write inhibit thresholds for individual heads for maximizing file servo performance
US6995941B1 (en) 2005-01-07 2006-02-07 Western Digital Technologies, Inc. Method for improving head position determination in a disk drive
US7110214B1 (en) 2005-01-18 2006-09-19 Western Digital Technologies, Inc. Disk drive to implement a seek operation utilizing a deceleration velocity profile that mathematically models BEMFs
US7489464B1 (en) 2005-02-02 2009-02-10 Western Digital Technologies, Inc. Servo writing a disk drive using a secondary actuator to control skew angle
US7050254B1 (en) 2005-02-11 2006-05-23 Western Digital Technologies, Inc. Internal disk drive temperature estimation
US7253989B1 (en) 2005-03-21 2007-08-07 Western Digital Technologies, Inc. Disk drive compensation of bias imparted by a flex circuit cable utilizing a dual bias curve estimation scheme
US7158329B1 (en) 2005-05-23 2007-01-02 Western Digital Technologies, Inc. Disk drive employing active braking using inductive sense
US7095579B1 (en) 2005-06-02 2006-08-22 Western Digital Technologies, Inc. Disk drive employing momentum based unload during power failure
US8724524B2 (en) 2005-06-10 2014-05-13 Panasonic Corporation Wireless communication apparatus and wireless communication method
US7265933B1 (en) 2005-06-14 2007-09-04 Western Digital Technologies, Inc. Disk drive computing repeatable run out while actuator arm is pressed against crash stop
US7196864B1 (en) 2005-06-15 2007-03-27 Western Digital Technologies, Inc. Disk drive having a servo control system optimized for faster determination of repeatable runout correction values and related method
US7304819B1 (en) 2005-06-23 2007-12-04 Western Digital Technologies, Inc. Method for writing repeatable runout correction values to a magnetic disk of a disk drive
US7199966B1 (en) 2005-06-28 2007-04-03 Western Digital Technologies, Inc. Disk drive adjusting seek profile for variable seek times to reduce power dissipation
US7088547B1 (en) 2005-07-25 2006-08-08 Western Digital Technologies, Inc. Disk drive recursively estimating repeatable runout
US7426086B2 (en) * 2005-08-24 2008-09-16 Hitachi Global Storage Technologies Off track write protection for data storage device
US7212374B1 (en) 2005-10-14 2007-05-01 Western Digital Technologies, Inc. Disk drive to characterize misaligned servo wedges
US7215504B1 (en) 2005-10-19 2007-05-08 Western Digital Technologies, Inc. Disk drive using an optical sensor to detect a position of an actuator arm
US7203021B1 (en) 2005-11-15 2007-04-10 Western Digital Technologies, Inc. Self-heating disk drive
US7474491B2 (en) 2005-12-09 2009-01-06 Maxtor Corporation Adaptive write unsafe thresholds for self servo writing
US20070139809A1 (en) 2005-12-09 2007-06-21 Maxtor Corporation Adaptive write unsafe thresholds for self servo writing
US7365932B1 (en) 2005-12-30 2008-04-29 Western Digital Technologies, Inc. Disk drive comprising an optical sensor for vibration mode compensation
US7495857B1 (en) 2005-12-30 2009-02-24 Western Digital Technologies, Inc. Servo writing a disk drive by writing spiral tracks using a mechanical position sensor
US7619844B1 (en) 2005-12-30 2009-11-17 Western Digital Technologies, Inc. Disk drive comprising a mechanical position sensor to prevent a runaway condition
US7480116B1 (en) 2006-01-20 2009-01-20 Western Digital Technologies, Inc. Disk drive employing coarse position feedback from mechanical position sensor to improve format efficiency
US7760461B1 (en) 2006-01-20 2010-07-20 Western Digital Technologies, Inc. Disk drive employing coarse position feedback from mechanical position sensor to improve format efficiency
US7701661B1 (en) 2006-01-20 2010-04-20 Western Digital Technologies, Inc. Disk drive employing coarse position feedback from mechanical position sensor to improve format efficiency
US7453661B1 (en) 2006-03-23 2008-11-18 Western Digital Technologies, Inc. Servo writing a disk drive with a controlled overlap near the middle diameter of the disk
US7289288B1 (en) 2006-03-23 2007-10-30 Western Digital Technologies, Inc. Disk drive having hybrid spindle speed control and related method
US7580212B1 (en) 2006-03-30 2009-08-25 Western Digital Technologies, Inc. Magnetic disk having efficiently stored WRRO compensation value redundancy information and method for using the redundancy information
US7423828B2 (en) * 2006-04-06 2008-09-09 Seagate Technology Llc Off-track write error recovery
US7339761B1 (en) 2006-04-18 2008-03-04 Western Digital Technologies, Inc. Method for wedge time shift calibration in a disk drive
US7595954B1 (en) 2006-04-18 2009-09-29 Western Digital Technologies, Inc. Disk drive to estimate repeatable runout (RRO) based upon on an optimal mean square estimation (MSE) learning method
US7298574B1 (en) 2006-05-10 2007-11-20 Western Digital Technologies, Inc. Servo writing a disk drive using correction values that attenuate phase error propagation
US7502192B1 (en) 2006-07-11 2009-03-10 Western Digital Technologies, Inc. Magnetic disk drive and method for efficiently determining and storing RRO compensation values using a secondary micro-actuator
US7391583B1 (en) 2006-07-27 2008-06-24 Western Digital Technologies, Inc. Fault tolerant sync mark detection while servo writing a disk drive from spiral tracks
US7333290B1 (en) 2006-08-03 2008-02-19 Western Digital Technologies, Inc. Magnetic disk in a disk drive and method having improved null servo burst phasing
US7457071B1 (en) 2006-08-08 2008-11-25 Western Digital Technologies, Inc. Locating an initial servo track in order to servo write a disk drive from spiral tracks
US7440225B1 (en) 2006-08-21 2008-10-21 Western Digital Technologies, Inc. Disk drive employing pivot friction compensation
US7466509B1 (en) 2006-09-22 2008-12-16 Western Digital Technologies, Inc. Disk drive operable with first and second servo patterns in a perpendicular media recording environment
US7388728B1 (en) 2006-09-22 2008-06-17 Western Digital Technologies, Inc. System and method for writing servo sectors in a perpendicular media recording environment
US7330019B1 (en) 2006-10-31 2008-02-12 Western Digital Technologies, Inc. Adjusting on-time for a discontinuous switching voltage regulator
US7450336B1 (en) 2006-10-31 2008-11-11 Western Digital Technologies, Inc. Method for improved repeatable run out learning in a disk drive
US7391584B1 (en) 2006-11-07 2008-06-24 Western Digital Technologies, Inc. Compensating for repeatable phase error when servo writing a disk drive from spiral tracks
US7542225B1 (en) 2006-11-17 2009-06-02 Western Digital Technologies, Inc. Disk drive idle mode responsive to flex circuit cable bias changes
US7616399B1 (en) 2006-12-07 2009-11-10 Western Digital Technologies, Inc. Disk drive servo control techniques to preserve PES continuity
US8643976B1 (en) 2007-01-31 2014-02-04 Western Digital Technologies, Inc. Method for improved repeatable runout learning in a disk drive
US20100035085A1 (en) 2007-02-03 2010-02-11 Wd Media, Inc. Perpendicular magnetic recording medium with improved magnetic anisotropy field
US7502197B1 (en) 2007-02-06 2009-03-10 Western Digital Technologies, Inc. Disk drive demodulating a time-based servo pattern
US7468855B1 (en) 2007-02-09 2008-12-23 Western Digital Technologies, Inc. Servo writing a disk drive from a number of spiral tracks equal to a non-integer multiple of product servo wedges
US7502195B1 (en) 2007-02-09 2009-03-10 Western Digital Technologies, Inc. Compensating for thermal expansion when writing spiral tracks to a disk of a disk drive
US7558016B1 (en) 2007-04-20 2009-07-07 Western Digital Technologies, Inc. Disk drive servo control techniques for predicting an off-track condition utilizing an estimation filter
US7477471B1 (en) 2007-04-20 2009-01-13 Western Digital Technologies, Inc. Disk drive employing offset compensation for velocity control of a voice coil motor
US7548392B1 (en) 2007-05-21 2009-06-16 Western Digital Technologies, Inc. Disk drive controlling a voice coil motor during an emergency unload
US7869155B1 (en) 2007-06-08 2011-01-11 Western Digital Technologies, Inc. Ramp detection during servo-writing of a disk for a disk drive
US7492546B1 (en) 2007-06-13 2009-02-17 Western Digital Technologies, Inc. Providing pre-determined servo position correction values for use during disk drive initialization
US7663835B1 (en) 2007-06-28 2010-02-16 Western Digital Technologies, Inc. System and method for identifying track squeeze errors (TSEs) of a disk of a disk drive
US7450334B1 (en) 2007-06-28 2008-11-11 Western Digital Technologies, Inc. Disk drive adjusting predictive caching based on temperature of voice coil motor
US7551390B1 (en) 2007-08-21 2009-06-23 Western Digital Technologies, Inc. Disk drive to characterize misaligned servo wedges
US7583470B1 (en) 2007-08-29 2009-09-01 Western Digital Technologies, Inc. Disk drive writing wedge RRO data along a sinusoidal path to compensate for reader/writer offset
US7505223B1 (en) 2007-09-05 2009-03-17 Western Digital Technologies, Inc. Compensating for non-linear thermal expansion when writing spiral tracks to a disk of a disk drive
US7733189B1 (en) 2007-09-14 2010-06-08 Western Digital Technologies, Inc. Oscillator comprising foldover detection
US7660067B1 (en) 2007-09-19 2010-02-09 Western Digital Technologies, Inc. Disk drive initializing a coil temperature estimation algorithm using a resistance of the coil estimated during a load operation
US7573670B1 (en) 2007-09-27 2009-08-11 Western Digital Technologies, Inc. Disk drive seeking to OD track and then ramping velocity to implement fast unload
US7576941B1 (en) 2007-10-26 2009-08-18 Western Digital Technologies, Inc. Disk drive writing wedge RRO values in a butterfly pattern
US7688538B1 (en) 2007-11-16 2010-03-30 Western Digital Technologies, Inc. Disk drive comprising a disk surface having track addresses of varying width
US7715138B1 (en) 2007-11-20 2010-05-11 Western Digital Technologies, Inc. Disk drive estimating a servo zone after synchronously detecting a servo sync mark
US7656604B1 (en) 2007-12-10 2010-02-02 Western Digital Technologies, Inc. Disk drive demodulating a spiral track by finding a maximum correlation between a spiral track crossing signal and a time-shifted nominal spiral track crossing signal
US7839595B1 (en) 2008-01-25 2010-11-23 Western Digital Technologies, Inc. Feed forward compensation for fly height control in a disk drive
US7852592B1 (en) 2008-01-29 2010-12-14 Western Digital Technologies, Inc. Spiral slope approximation of spiral patterns written to a disk of a disk drive
US7630162B2 (en) 2008-02-04 2009-12-08 Western Digital Technologies, Inc. Disk drive servoing off of first head while determining fly height for second head
US8780473B1 (en) 2008-02-04 2014-07-15 Western Digital Technologies, Inc. Disk drive selecting a global digital-to-analog setting for a plurality of heads
US7839591B1 (en) 2008-02-11 2010-11-23 Western Digital Technologies, Inc. Disk drive comprising index spiral track identified by change in sync mark
US7639447B1 (en) 2008-02-18 2009-12-29 Western Digital Technologies, Inc. Servo track squeeze compensation in a disk drive
US8482873B1 (en) 2008-02-18 2013-07-09 Western Digital Technologies, Inc. Disk drive employing pulse width modulation of head control signal
US7710676B1 (en) 2008-03-27 2010-05-04 Western Digital Technologies, Inc. Disk drive comprising gray code implemented with servo bursts
US7916415B1 (en) 2008-03-27 2011-03-29 Western Digital Technologies, Inc. Disk drive decoding binary sequence from phases of servo bursts
US7688539B1 (en) 2008-05-14 2010-03-30 Western Digital Technologies, Inc. Disk drive self servo writing spiral tracks by propagating bursts
US7602575B1 (en) 2008-05-14 2009-10-13 Western Digital Technologies, Inc. Disk drive adjusting estimated reader/writer offset to achieve target burst crossing signal amplitude when propagating servo sectors
US7843662B1 (en) 2008-06-10 2010-11-30 Western Digital Technologies, Inc. Servoing on concentric servo sectors of a first disk surface to write a spiral servo track to a second disk surface
US8085020B1 (en) 2008-06-13 2011-12-27 Western Digital Technologies, Inc. Switching voltage regulator employing dynamic voltage scaling with hysteretic comparator
US8078901B1 (en) 2008-06-16 2011-12-13 Western Digital Technologies, Inc. Method for increasing a processor operating frequency when other subsystem demands are low
US7852588B1 (en) 2008-06-23 2010-12-14 Western Digital Technologies, Inc. Disk drive adjusting gain of shock detector relative to resonant frequency amplitude
US8054022B1 (en) 2008-06-26 2011-11-08 Western Digital Technologies, Inc. Reduced acoustic noise during spin-up by driving a spindle motor open loop using sinusoidal signals
US7626782B1 (en) 2008-07-23 2009-12-01 Western Digital Technologies, Inc. Disk drive employing iterative learning control for tuning seek servo loop
US7746594B1 (en) 2008-09-29 2010-06-29 Western Digital Technologies, Inc. Disk drive comprising slanted line servo burst sets offset radially
US7746595B1 (en) 2008-09-29 2010-06-29 Western Digital Technologies, Inc. Disk drive comprising slanted line servo bursts having reverse polarity segments
US7916416B1 (en) 2008-09-29 2011-03-29 Western Digital Technologies, Inc. Disk drive comprising slanted line servo bursts having a varying tilt angle
US7876522B1 (en) 2008-09-30 2011-01-25 Western Digital Technologies, Inc. Disk drive updating estimate of voice coil resistance to account for resistance change prior to unload operation
US7929238B1 (en) 2008-10-14 2011-04-19 Western Digital Technologies, Inc. Disk drive seeking with a fixed rate clock when crossing servo zones to facilitate zoned servo sectors
US7697233B1 (en) 2008-10-21 2010-04-13 Western Digital Technologies, Inc. Disk drive comprising a servo accelerator implementing state space equations for a plurality of task objects
US7656607B1 (en) 2008-10-21 2010-02-02 Western Digital Technologies, Inc. Disk drive comprising a servo accelerator employing a dual state variable memory
US7679854B1 (en) 2008-10-29 2010-03-16 Western Digital Technologies, Inc. Head switch operation for a disk drive
US7675707B1 (en) 2008-11-21 2010-03-09 Western Digital Technologies, Inc. Disk drive employing repeatable disturbance compensation for fly height control
US7800853B1 (en) 2008-12-03 2010-09-21 Western Digital Technologies, Inc. Correcting servo sectors in a disk drive
US7688534B1 (en) 2008-12-11 2010-03-30 Western Digital Technologies, Inc. Extracting repeatable phase error from a spindle motor back EMF signal to generate a servo write clock
US8116023B1 (en) 2008-12-15 2012-02-14 Western Digital Technologies, Inc. Disk drive comprising preamble aligned zoned servo sectors
US8000053B1 (en) 2008-12-23 2011-08-16 Western Digital Technologies, Inc. Write jog value determination for a disk drive
US7729079B1 (en) 2009-01-21 2010-06-01 Western Digital Technologies, Inc. Disk drive estimating fly height using a PLL tuned by a fly height capacitance
US7864481B1 (en) 2009-01-26 2011-01-04 Western Digital Technologies, Inc. Evaluating distribution of peak signals representing reference track crossings to compensate for thermal expansion when writing spiral tracks to a disk
US7746592B1 (en) 2009-02-13 2010-06-29 Western Digital Technologies, Inc. Disk drive detecting defective spiral servo track
US7961422B1 (en) 2009-02-19 2011-06-14 Western Digital Technologies, Inc. Disk drive computing data center off-track from repeatable runout of write servo track and read servo track
US7864482B1 (en) 2009-02-27 2011-01-04 Western Digital Technologies, Inc. Disk drive calibrating VCM notch filter by increasing the width and/or the depth of the notch
US8213106B1 (en) 2009-03-10 2012-07-03 Western Digital Technologies, Inc. Zoned servo system
US7800856B1 (en) 2009-03-24 2010-09-21 Western Digital Technologies, Inc. Disk drive flushing write cache to a nearest set of reserved tracks during a power failure
US20100265611A1 (en) 2009-04-20 2010-10-21 Samsung Electronics Co., Ltd. Controller, disk drive having the controller, and data processing system having the disk drive
US8358114B1 (en) 2009-04-28 2013-01-22 Western Digital Technologies, Inc. Output capacitor current as feedback to control a hysteretic voltage regulator
US7800857B1 (en) 2009-04-30 2010-09-21 Western Digital Technologies, Inc. Disk drive calibrating voice coil resistance for velocity control of voice coil motor
US7839600B1 (en) 2009-05-04 2010-11-23 Western Digital Technologies, Inc. Disk drive employing data-based basis function expansion for tuning seek servo loop
US8358145B1 (en) 2009-06-19 2013-01-22 Western Digital Technologies, Inc. Self-heating integrated circuit
US8031423B1 (en) 2009-06-26 2011-10-04 Western Digital Technologies, Inc. Disk drive generating actual data TPI profile by combining segments of predetermined data TPI profiles
US8145934B1 (en) 2009-07-31 2012-03-27 Western Digital Technologies, Inc. Soft start sequencer for starting multiple voltage regulators
US7876523B1 (en) 2009-08-07 2011-01-25 Western Digital Technologies, Inc. Disk drive initializing position feedforward compensation with velocity feedforward compensation
US8351174B1 (en) 2009-10-29 2013-01-08 Western Digital Technologies, Inc. Apparatus comprising a brown-out protection circuit for memory devices
US8315005B1 (en) 2009-11-06 2012-11-20 Western Digital Technologies, Inc. Ramp detection by profile sweep method utilizing integrator values
US8179626B1 (en) 2009-12-04 2012-05-15 Western Digital Technologies, Inc. Adaptive shock detection
US8081395B1 (en) 2009-12-15 2011-12-20 Western Digital Technologies, Inc. Continuous digital offset cancellation
US8779574B1 (en) 2009-12-22 2014-07-15 Western Digital Technologies, Inc. Semiconductor die including a current routing line having non-metallic slots
US8432031B1 (en) 2009-12-22 2013-04-30 Western Digital Technologies, Inc. Semiconductor die including a current routing line having non-metallic slots
US8665546B1 (en) 2010-01-07 2014-03-04 Western Digital Technologies, Inc. Adaptive threshold for detecting touchdown or contamination
US8059357B1 (en) 2010-03-18 2011-11-15 Western Digital Technologies, Inc. Disk drive adjusting fly height when calibrating head/disk contact
US8320069B1 (en) 2010-03-18 2012-11-27 Western Digital Technologies, Inc. Disk drive detecting positive correlation in fly height measurements
US8498076B1 (en) 2010-04-22 2013-07-30 Western Digital Technologies, Inc. Disk drive biasing timing recovery measurements for spiral tracks based on radial location of head
US7916420B1 (en) 2010-05-14 2011-03-29 Western Digital Technologies, Inc. Disk drive employing comb filter for repeatable fly height compensation
US8189286B1 (en) 2010-05-21 2012-05-29 Western Digital Technologies, Inc. Disk drive employing velocity insensitive servo burst pattern
US7916422B1 (en) 2010-05-28 2011-03-29 Western Digital Technologies, Inc. Disk drive rotating phase based servo bursts based on radial location of head
US8059360B1 (en) 2010-06-22 2011-11-15 Western Digital Technologies, Inc. Disk drive compensating for radial phase change of repeatable position error due to servo writing from spiral tracks
US8077428B1 (en) 2010-06-23 2011-12-13 Western Digital Technologies, Inc. Disk drive correcting position error signal based on velocity of head
US8072703B1 (en) 2010-06-23 2011-12-06 Western Digital Technologies, Inc. Disk drive detecting when head is parked on ramp
US8300348B1 (en) 2010-06-25 2012-10-30 Western Digital Technologies, Inc. Disk drive detecting disk boundaries using microactuator
US8498172B1 (en) 2010-08-31 2013-07-30 Western Digital Technologies, Inc. Data storage device evaluating frequency range of supply voltage to detect power failure
US8687312B1 (en) 2010-11-30 2014-04-01 Western Digital Technologies, Inc. Edge detection for disk drives
US8531798B1 (en) 2010-12-13 2013-09-10 Western Digital Technologies, Inc. Disk drive adjusting servo burst signals to compensate for radial velocity of the head
US20120162806A1 (en) 2010-12-23 2012-06-28 Western Digital Technologies, Inc. Directional write retry for shingled disk drive application
US8619385B1 (en) 2011-01-28 2013-12-31 Western Digital Technologies, Inc. Disk drive biasing sync pattern of an extended sync mark
US8390367B1 (en) 2011-02-15 2013-03-05 Western Digital Technologies, Inc. Ensuring minimum gate speed during startup of gate speed regulator
US8254222B1 (en) 2011-03-21 2012-08-28 Western Digital Technologies, Inc. Disk drive tuning dual stage actuator servo loop gains from open loop response at target frequency
US8625215B1 (en) * 2011-03-21 2014-01-07 Marvell International Ltd. Method and system for compensating for adjacent tracks during writing of data
US20120284493A1 (en) 2011-05-03 2012-11-08 Western Digital Technologies, Inc. Booting from a secondary storage device in order to accumulate disk drive performance data
US8737008B1 (en) 2011-05-12 2014-05-27 Western Digital Technologies, Inc. Disk drive adjusting gain of spindle motor compensator based on a ratio of spin speeds
US8432629B1 (en) 2011-05-23 2013-04-30 Western Digital Technologies, Inc. Disk drive centering sync frames on sync marks of a spiral track
US8451697B1 (en) 2011-05-23 2013-05-28 Western Digital Technologies, Inc. Disk drive centering demodulation windows on spiral tracks during a seek operation
US8508881B1 (en) 2011-05-26 2013-08-13 Western Digital Technologies, Inc. Disk drive employing system inversion for tuning seek to settle servo loop
US20120307400A1 (en) 2011-05-31 2012-12-06 Kabushiki Kaisha Toshiba Disk storage apparatus, disk control apparatus and write control method
US8743495B1 (en) 2011-06-03 2014-06-03 Western Digital Technologies, Inc. Disk drive detecting track squeeze when circular tracks are defined from non-circular servo tracks
US8760796B1 (en) 2011-06-03 2014-06-24 Western Digital Technologies, Inc. Reducing acoustic noise in a disk drive when exiting idle mode
US8605382B1 (en) 2011-06-08 2013-12-10 Western Digital Technologies, Inc. Disk drive to load a head to a load/unload (LUL) zone of a disk
US8693134B1 (en) 2011-06-23 2014-04-08 Western Digital Technologies, Inc. Alternating wedge repeatable runout (WRRO) pattern
US8693123B1 (en) 2011-06-27 2014-04-08 Western Digital Technologies, Inc. Disk drive correcting high order gray code using track estimator and decoding low order track code separately
US8610391B1 (en) 2011-06-29 2013-12-17 Western Digital Technologies, Inc. Disk drive optimizing spindle motor torque by adjusting leading phase angle during spin-up
US8634154B1 (en) 2011-08-08 2014-01-21 Western Digital Technologies, Inc. Disk drive writing a sync mark seam in a bootstrap spiral track
US8634283B1 (en) 2011-08-08 2014-01-21 Western Digital Technologies, Inc. Disk drive performing in-drive spiral track writing
US8564899B2 (en) 2011-08-09 2013-10-22 Western Digital Technologies, Inc. Disk drive decreasing a settle delay based on speed that a settle parameter adapts
US8537486B2 (en) 2011-08-10 2013-09-17 Western Digital Technologies, Inc. Disk drive writing spiral tracks on a slave surface using repeatable runout compensation for a master surface
US8699173B1 (en) 2011-09-01 2014-04-15 Western Digital Technologies, Inc. Disk drive detecting touchdown event by evaluating frequency response of a touchdown metric
US8630054B2 (en) 2011-09-21 2014-01-14 Western Digital Technologies, Inc. Systems and methods for data throttling during disk drive power down
US8553351B1 (en) 2011-10-06 2013-10-08 Western Digital Technologies, Inc. Disk drive correcting track ID in response to an estimated radial location and a burst PES
US8542455B2 (en) 2011-11-16 2013-09-24 Western Digital Technologies, Inc. Disk drive upsampling servo control signal
US8737013B2 (en) 2011-11-16 2014-05-27 Western Digital Technologies, Inc. Disk drive selecting disturbance signal for feed-forward compensation
US20130120870A1 (en) 2011-11-16 2013-05-16 Western Digital Technologies, Inc. Disk drive selecting disturbance signal for feed-forward compensation
US8654466B1 (en) 2011-11-21 2014-02-18 Western Digital Technologies, Inc. Calculation of head media separation (HMS) from servo preamble in a hard disk drive
US8767354B1 (en) 2011-12-08 2014-07-01 Western Digital Technologies, Inc. Data storage device employing cascaded voltage regulators during power failure
US20130148240A1 (en) 2011-12-09 2013-06-13 Western Digital Technologies, Inc. Disk drive charging capacitor using motor supply voltage during power failure
US8665551B1 (en) 2011-12-22 2014-03-04 Western Digital Technologies, Inc. Disk drive adjusting gain and offset of BEMF velocity sensor during self writing of spiral tracks
US8717699B1 (en) 2012-01-10 2014-05-06 Western Digital Technologies, Inc. Voltage quadrupler comprising a second charging capacitor charged using a first charging capacitor
US8717704B1 (en) 2012-02-28 2014-05-06 Western Digital Technologies, Inc. Disk drive defining non-circular data tracks relative to a rotation axis of the disk
US8749904B1 (en) 2012-02-28 2014-06-10 Western Digital Technologies, Inc. Disk drive compensating for track squeeze by writing non-circular servo tracks
US8630059B1 (en) 2012-02-29 2014-01-14 Western Digital Technologies, Inc. Methods for closed-loop compensation of ultra-high frequency disturbances in hard disk drives and hard disk drives utilizing same
US8824081B1 (en) 2012-03-13 2014-09-02 Western Digital Technologies, Inc. Disk drive employing radially coherent reference pattern for servo burst demodulation and fly height measurement
US8724253B1 (en) 2012-03-27 2014-05-13 Western Digital Technologies, Inc. Disk drive adjusting demodulation window for spiral track using timing feed-forward compensation
US8670206B1 (en) 2012-03-27 2014-03-11 Western Digital Technologies, Inc. Disk drive estimating repeatable runout of reference pattern based on repeatable runout of phase error
US8649121B1 (en) 2012-03-28 2014-02-11 Western Digital Technologies, Inc. Disk drive tuning speed control loop for a spindle motor
US8773787B1 (en) 2012-03-29 2014-07-08 Western Digital Technologies, Inc. Changing the performance level of a disk drive
US8654467B1 (en) 2012-04-16 2014-02-18 Western Digital Technologies, Inc. Disk drive increasing bandwidth of cutoff filter while reading servo sector preamble
US8767343B1 (en) 2012-04-24 2014-07-01 Western Digital Technologies, Inc. Disk drive increasing integrator output range to complete seek operation
US8780477B1 (en) 2012-06-21 2014-07-15 Western Digital Technologies, Inc. Disk drive adjusting servo timing to compensate for transient when crossing a servo zone boundary
US8576506B1 (en) 2012-06-21 2013-11-05 Western Digital Technologies, Inc. Disk drive estimating reader/writer gap across servo zones
US8724245B1 (en) 2012-06-21 2014-05-13 Western Digital Technologies, Inc. Disk drive employing overlapping servo zones to facilitate servo zone crossing
US8743504B1 (en) 2012-07-25 2014-06-03 Western Digital Technologies, Inc. Servoing on zoned concentric servo sectors of a first disk surface to write a spiral servo track to a second disk surface
US8611040B1 (en) 2012-09-27 2013-12-17 Western Digital Technologies, Inc. Disk drive adjusting microactuator gain by injecting a sinusoid into a servo control system
US8605384B1 (en) 2012-11-06 2013-12-10 Western Digital Technologies, Inc. Disk drive performing lifetime logging of microactuator sensitivity
US8804267B2 (en) 2012-11-07 2014-08-12 Western Digital Technologies, Inc. Disk drive predicting spindle motor failure by evaluating current draw relative to temperature
US8711027B1 (en) 2012-11-19 2014-04-29 Western Digital Technologies, Inc. Analog-to-digital converter with input voltage biasing DC level of resonant oscillator
US8780489B1 (en) 2012-11-20 2014-07-15 Western Digital Technologies, Inc. Disk drive estimating microactuator gain by injecting a sinusoid into a closed loop servo system
US8717696B1 (en) 2012-12-04 2014-05-06 Western Digital Technologies, Inc. Disk drive adjusting noise spectrum to reduce resonance excitation of shock detector
US8797664B1 (en) 2012-12-22 2014-08-05 Western Digital Technologies, Inc. Polarity detection of piezoelectric actuator in disk drive
US8743503B1 (en) 2013-03-11 2014-06-03 Western Digital Technologies, Inc. Disk drive updating compensation values for multiple servo sectors based on PES generated for current servo sector
US8767332B1 (en) 2013-04-03 2014-07-01 Western Digital Technologies, Inc. Disk drive predicting off-track error due to disturbances occurring over different frequency ranges
US8780479B1 (en) 2013-05-17 2014-07-15 Western Digital Technologies, Inc. Disk drive executing jerk seeks to rotate pivot ball bearings relative to races
US8824262B1 (en) 2013-08-19 2014-09-02 Western Digital Technologies, Inc. Disk drive accounting for sinusoidal offset between heads when executing a rotational position optimization algorithm
US8792202B1 (en) 2013-08-29 2014-07-29 Western Digital Technologies, Inc. Disk drive adjusting rotation speed of disk to compensate for blind area when measuring frequency response of servo control system

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
Daniel J. Gunderson, et al., U.S. Appl. No. 13/246,600, filed Sep. 27, 2011, 17 pgs.
Notice of Allowance dated Sep. 9, 2012 from U.S. Appl. No. 13/911,365, 46 pages.
Office Action dated Apr. 24, 2014 from U.S. Appl. No. 13/911,365, 15 pages.
Wei Xi , et al., U.S. Appl. No. 13/911,365, filed Jun. 6, 2013, 20 pages.

Similar Documents

Publication Publication Date Title
US7852592B1 (en) Spiral slope approximation of spiral patterns written to a disk of a disk drive
US8767343B1 (en) Disk drive increasing integrator output range to complete seek operation
US7864481B1 (en) Evaluating distribution of peak signals representing reference track crossings to compensate for thermal expansion when writing spiral tracks to a disk
US8743495B1 (en) Disk drive detecting track squeeze when circular tracks are defined from non-circular servo tracks
US7372650B1 (en) Rotating media storage device having a calibration track with unique calibration servo synch marks
US8717695B1 (en) Characterizing head parameters of a disk drive by evaluating track profile of an overwritten track
US8194341B1 (en) Disk drive seeding data path protection with system data seed
US7933087B1 (en) Disk drive storing parameters of a write operation in a plurality of data sectors
US8432629B1 (en) Disk drive centering sync frames on sync marks of a spiral track
US7900037B1 (en) Disk drive maintaining multiple logs to expedite boot operation for a host computer
US8694841B1 (en) Methods and devices for preventing potential media errors from growing thermal asperities
US6490691B1 (en) Error recovery in a disk drive
US7656603B1 (en) Pre-programming of a preamplifier in a disk drive to improve servo-writing characteristics
US8717704B1 (en) Disk drive defining non-circular data tracks relative to a rotation axis of the disk
US6469859B1 (en) Method and system for accurate self-servowriting with normalization in a disk drive
US7929234B1 (en) Disk drive prioritizing in-the-field defect scanning based on number of write operations in each of a plurality of defect zones
US8693134B1 (en) Alternating wedge repeatable runout (WRRO) pattern
US8755143B2 (en) Disk drive adjusting rotational position optimization (RPO) algorithm to compensate for repeatable runout (RRO)
US8611031B1 (en) Methods and devices for adaptive margining
US7663835B1 (en) System and method for identifying track squeeze errors (TSEs) of a disk of a disk drive
US7154689B1 (en) Apparatus for writing servo bursts on a disk with servo track pitch based on read element width and methods of manufacturing same
US8699185B1 (en) Disk drive defining guard bands to support zone sequentiality when butterfly writing shingled data tracks
US7843660B1 (en) Disk drive adjusting erasure window based on a number of non-read data sectors during a retry operation
US8792196B1 (en) Disk drive estimating noise in a read signal based on an identified response at the input of an equalizer
US8493679B1 (en) Disk drive implementing a read channel optimization process

Legal Events

Date Code Title Description
AS Assignment

Owner name: WESTERN DIGITAL TECHNOLOGIES, INC., CALIFORNIA

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:SANTEE, NATHAN J.;HUANG, YANAN;XI, WEI;AND OTHERS;SIGNING DATES FROM 20150706 TO 20150710;REEL/FRAME:036448/0601

AS Assignment

Owner name: JPMORGAN CHASE BANK, N.A., AS COLLATERAL AGENT, IL

Free format text: SECURITY AGREEMENT;ASSIGNOR:WESTERN DIGITAL TECHNOLOGIES, INC.;REEL/FRAME:038722/0229

Effective date: 20160512

Owner name: U.S. BANK NATIONAL ASSOCIATION, AS COLLATERAL AGEN

Free format text: SECURITY AGREEMENT;ASSIGNOR:WESTERN DIGITAL TECHNOLOGIES, INC.;REEL/FRAME:038744/0281

Effective date: 20160512

Owner name: JPMORGAN CHASE BANK, N.A., AS COLLATERAL AGENT, IL

Free format text: SECURITY AGREEMENT;ASSIGNOR:WESTERN DIGITAL TECHNOLOGIES, INC.;REEL/FRAME:038744/0481

Effective date: 20160512